Compositions comprising functionalized carbon-based nanostructures and related methods

ABSTRACT

The present invention generally relates to compositions comprising and methods for forming functionalized carbon-based nanostructures.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 61/409,844, filed Nov. 3, 2010, andentitled “Compositions Comprising and Methods for Forming FunctionalizedCarbon-Based Nanostructures” which is incorporated herein by referencein its entirety for all purposes.

FIELD OF THE INVENTION

The present invention generally relates to compositions comprising andmethods for forming or using functionalized carbon-based nanostructures.

BACKGROUND OF THE INVENTION

Carbon-based nanostructures, including two-dimensional graphenenanosheets and graphene-based materials, have garnered an increasinglylarge amount of scientific interest in recent years due to theirstructural and electronic properties. Conventional methods forsynthesizing graphene-based materials utilize graphite oxide (GO) as astarting material, which can be prepared in bulk quantities fromcommercial-grade graphite under strong oxidizing conditions. GO in itsbulk form is a layered material composed of a variety ofoxygen-containing functionalities, for example, epoxides and tertiaryalcohol groups are generally found on the basal plane and carbonyl andcarboxyl groups along the sheet edges. The diversity and density offunctionality in GO provides a platform for chemistry to occur bothwithin the intersheet gallery and along sheet edges.

Despite the recent upsurge in methods for forming graphene derivativesalong with subsequent incorporation of the products into graphene-baseddevices, only a few methods exist to covalently functionalize the basalplane of graphene. Moreover, current methodology often introduces basalplane functionalities that are weakly bound to the graphene surfacethrough carbon-oxygen (C—O) or carbon-nitrogen (C—N) bonds andtherefore, the resulting material generally cannot survive furtherthermal, electrochemical, and/or chemical treatment of thegraphene-based material. The labile nature of such chemicalfunctionalities represents a significant drawback to the currentlyavailable technology, as in many cases it is necessary to deoxygenatethe graphene derivatives under relatively harsh conditions toreestablish electrical conductivity within the graphene nanosheet.Additionally, incorporation of these C—O or C—N modified graphenematerials into devices can intrinsically limit the thermal and/orelectrochemical boundaries of the device.

SUMMARY OF THE INVENTION

In some aspects of the present invention, compositions are provided. Insome embodiments, a composition comprises graphene or graphene oxidecomprising at least one functional group associated with the graphene orgraphene oxide, wherein the at least one functional group has thestructure:

wherein R¹, R², and R³ are the same or different and each isindependently a substituent, optionally substituted; and G comprises acarbon atom of the graphene or graphene oxide

In other aspects of the present invention, methods are provided. In someembodiments, a method for fabricating a functionalized carbon-basednanostructure comprises providing a carbon-based nanostructurecomprising an allylic functional group, reacting the carbon-basednanostructure with a reactant comprising at least one carbon atom, andcausing a carbon-carbon bond to form between the at least one carbonatom within the reactant and a carbon atom within the carbon-basednanostructure. In another embodiment, a method for fabricating afunctionalized carbon-based nanostructure comprises providing acarbon-based nanostructure including a group

wherein C¹, C², and C³ are part of a fused network of aromatic ringswithin the carbon-based nanostructure and OR⁵ is a pendant group of thefused network of aromatic rings, wherein R⁵ is a substituent, optionallysubstituted, and reacting the carbon-based nanostructure with a reactantto produce a group having formula (II):

wherein R⁶, R⁷, and R⁸ are the same or different and each isindependently a substituent, optionally substituted.

In some embodiments, a device comprising a composition as describedherein and/or a composition formed using a method as described hereinare provided. In another aspect, the present invention encompassesmethods of making one or more of the embodiments described herein. Instill another aspect, the present invention encompasses methods of usingone or more of the embodiments described herein.

In some embodiments, a method for reducing the amount of an species in asample is provided. In some cases, the method comprises contacting avapor phase sample containing a first concentration of the species witha composition comprising substituted graphene or graphene oxidemolecules such that the vapor phase sample has a second, decreasedconcentration of the species after contact with the composition.

In some embodiments, the method comprises contacting a sample containinga first concentration of the species with a composition comprisinggraphene or graphene oxide, wherein the graphene or graphene oxidecomprises at least one functional group

wherein R¹, R², and R³ are the same or different and each is asubstituent, optionally substituted; and

G comprises a carbon atom of the graphene or graphene oxide,

such that the sample has a second, decreased concentration of speciesafter contact with the composition.

In some embodiments, a catalyst composition is provided. In some cases,the catalyst composition comprises a graphene or graphene oxide moleculecomprising at least one functional group having the structure:

wherein:

R¹, R², and R³ are the same or different and each is independently asubstituent, optionally substituted, wherein at least one of R¹, R², andR³ comprises a catalytic moiety capable of oxidizing carbon monoxide tocarbon dioxide; and

G comprises a carbon atom of the graphene or graphene oxide.

In some embodiments, the method comprises contacting a sample comprisingcarbon monoxide with a graphene or graphene oxide molecule comprising atleast one functional group having the structure:

wherein:

R¹, R², and R³ are the same or different and each is independentlyhydrogen or a substituent, optionally substituted; and

G comprises a carbon atom of the graphene or graphene oxide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows non-limiting images of a reaction of the present invention,according to some embodiments.

FIGS. 2A-2B show XPS data of materials, including materials of thepresent invention, according to some embodiments.

FIGS. 3A-3B show hi-res XPS data of materials, including materials ofthe present invention, according to some embodiments.

FIG. 4 shows TGA and dTGA spectra of materials, including materials ofthe present invention, according to some embodiments.

FIG. 5 shows XRD spectra of materials, including materials of thepresent invention, according to some embodiments.

FIG. 6 shows FTIR spectra of materials, including materials of thepresent invention, according to some embodiments.

FIG. 7 shows solutions of materials of the present invention, accordingto some embodiments.

FIG. 8 shows an illustrative example of protonated and unprotonatedforms of functionalized graphene, according to some embodiments.

FIG. 9 shows an oxidized graphene sheet functionalized with amide groupsundergoing a redox reaction such that charge from the graphene layer isdelocalized onto the amide nitrogen.

FIG. 10 shows the conversion of carbon-oxygen bonds on a graphite oxidebasal plane to carbon-bound carbonyl groups.

FIG. 11 shows (a) synthesis of allylic amide-functionalized graphene;(b) a space-filling model of the synthesis of allylicamide-functionalized graphene; (c) a photograph of a solution ofgraphene oxide and an aliquot taken 1 hour after the reaction ofgraphene oxide with [(CH₃)₂N]C(OCH₃)₂CH₃; (d) an FTIR spectrum ofallylic amide-functionalized graphene oxide; (e) and X-ray diffractionplot for graphite, graphene oxide, and allylic amide-functionalizedgraphene oxide; (f) X-ray photoelectron spectroscopy (XPS) plots forgraphene oxide, and allylic amide-functionalized graphene oxide; and (g)XPS data for graphene oxide, and allylic amide-functionalized grapheneoxide.

FIG. 12 shows (a) the saponification of an allylic ester-functionalizedgraphene oxide; (b) XPS data and (c) XPS plot for a carboxylicacid-functionalized graphene oxide.

FIG. 13 shows (a) the reversible conversion of carboxylicacid-functionalized graphene oxide to a potassium saltcarboxylate-functionalized graphene oxide; (b) the reversible formationof aqueous colloids containing potassium salt carboxylate-functionalizedgraphene oxide from carboxylic acid-functionalized graphene oxide; (c) aphotograph of solutions of carboxylic acid-functionalized graphene oxideunder various conditions; (d) zeta potential and conductivity data forcarboxylic acid-functionalized graphene oxides.

FIG. 14 shows (a) the synthesis of allyl allylic ester-functionalizedgraphene oxide via a Johnson-Claisen rearrangement; (b) saponificationof an allyl allylic ester-functionalized graphene oxide; (c)transamidation of an allyl allylic ester-functionalized graphene oxide;(d) synthesis of graphene oxides with functional group containing analkyne for “click” chemistry reactions; (e) an FTIR spectrum of grapheneoxide substituted with —CH₂(C═O)NHCH₂CCH; (f) FTIR spectra for varioussubstituted graphene oxides; and (g) XRD plots for various substitutedgraphene oxides.

FIG. 15 shows (a) the synthesis of functionalized graphene oxides via aCarroll rearrangement; (b) illustrative reaction conditions forsynthesizing functionalized graphene oxides via a Carroll rearrangement;(c) formation of an acyl ketene according to one embodiment; (d)formation of an acyl ketene according to another embodiment; (e)illustrative embodiments for synthesis of functionalized grapheneoxides.

FIG. 16 shows thermogravimetric analysis data for various functionalizedgraphenes compared to unsubstituted graphene and unsubstituted graphenewith physioadsorbed groups.

FIG. 17 shows X-ray diffraction data for graphene covalentlyfunctionalized on the basal plane.

FIG. 18 shows XPS data for graphene covalently functionalized on thebasal plane.

FIG. 19 shows a photograph of various samples containing covalentlyfunctionalized graphene, graphene with physioadsorbed groups, andunsubstituted graphene.

FIG. 20 shows the use of a composition described herein as a filter forcigarette smoke.

Other aspects, embodiments, and features of the invention will becomeapparent from the following detailed description when considered inconjunction with the accompanying drawings. The accompanying figures areschematic and are not intended to be drawn to scale. For purposes ofclarity, not every component is labeled in every figure, nor is everycomponent of each embodiment of the invention shown where illustrationis not necessary to allow those of ordinary skill in the art tounderstand the invention. All patent applications and patentsincorporated herein by reference are incorporated by reference in theirentirety. In case of conflict, the present specification, includingdefinitions, will control.

DETAILED DESCRIPTION

The present invention generally relates to compositions comprisingfunctionalized carbon-based nanostructures such as functionalizedgraphene nanosheets, and related methods. Functionalized graphene-basedmaterials and other carbon-based nanostructures may find use in manyapplications, such as those described herein. Some embodiments of theinvention enhance the processability and/or solubility of carbon-basednanostructures (e.g., graphene and graphene-based materials), forexample, for use with such applications.

In some embodiments, the present invention provides methods which allowfor relatively large-scale production of functionalized graphene (e.g.,graphene nanosheets) using graphene oxide as the bulk starting material.Graphene oxide will be known to those of ordinary skill in the art andgenerally refers to an oxygenated form of the common carbon allotropegraphene, and is readily available and generally inexpensive. Themethods described herein not only allow for chemically functionalizingthe graphene oxide, but also may allow for subsequent deoxygenation ofthe graphene oxide following functionalization, e.g., without causingdisassociation or decomposition of the chemical functionalities. Forexample, a two-step procedure can be utilized according to certainembodiments, comprising 1) oxidation with concomitant exfoliation tographene oxide, and 2) chemical, electrochemical, or thermal reductionto reestablish molecular conjugation and conductivity of the grapheneoxide.

In some cases, the method comprises functionalizing graphene oxide witha plurality of functional groups, wherein each functional group isassociated with (e.g., attached to) the graphene network via acarbon-carbon bond. The carbon-carbon bond formed duringfunctionalization may be capable of withstanding conditions necessaryfor further functionalizing the graphene and/or the functional groups,and/or reduction of the graphene. In some cases, the methods utilizerelatively non-toxic and/or essentially non-toxic materials as comparedto currently known methods.

In some embodiments, the compositions and methods described hereinprovide carbon-based nanostructures, such as graphene oxide or graphene,comprising functional groups associated with the carbon-basednanostructure, generally via a carbon-carbon bond, wherein thefunctional group comprise a carbonyl group (e.g., ester, carboxylicacid, carboxylate, aldehyde, amide, ketone, any of which is optionallysubstituted). In some cases, the carbonyl group is an allylic carbonylgroup. The carbonyl groups may be further functionalized and may provideaccess to materials useful in a variety of applications. For example,the carbonyl groups may bind metal ions, and may find use as molecularscaffolds for metal nanoparticles (e.g., for catalytic processes, forchemosensing) or to trap metal ions. In some cases, the compositions canbe used as an n-type material (e.g., electron transport semiconductor)for various applications including quantum-dot based photovoltaic cells.In other cases, the compositions may be used as an anode and/or cathodematerial, e.g., to bind lithium ions in lithium ion batteries, ingraphene-nanoparticle hybrid batteries. Additionally, the carbonylgroups may be themselves functionalized, thereby allowing for additionaltuning of the structural and/or electronic properties of thecomposition. For example, amide functionalized materials may displayexpanded intersheet distances (e.g., in comparison to graphite andchemically reduced graphene) and/or high surface areas, and may findapplication as supercapacitors. Additional applications and uses andwell as functionalization of the carbonyl groups are described herein.

The methods and/or compositions described herein provide numerousadvantages and/or improvements over current methods and/or compositions.For example, while known methods for functionalizing graphene withcarbon-carbon bonds generally utilize either unstable colloidalsolutions of preformed graphene nanosheets (e.g., arylation methods) orair and/or water sensitive metal-intercalated graphite (e.g., alkylationmethods), the methods described herein generally utilize air and water(bench-stable) graphite oxide (GO) as the starting material for thechemical transformation. The methods and/or compositions also maycomprise high functional group densities, as described herein, which aregenerally higher than known methods/compositions. In addition, themethods described herein can be conducted on large scales (e.g.,kilotons of product). Furthermore, many of the methods and systemsdiscussed herein are applicable not only to graphene oxide, but to othercarbon-based nanomaterials as well, for example, carbon nanotubes(single or multi-walled), fullerenes, or the like. Further examples ofcarbon-based nanomaterials are described in detail below.

In some embodiments of the present invention, compositions are provided.In some cases, the composition comprises graphene or graphene oxideassociated with at least one functional group. A functional group may bebound to (e.g., attached to) the graphene network via a carbon-carbonbond (e.g., a carbon-carbon single bond), where one of the carbon atomsforming the carbon-carbon bond is not itself part of the mesh or fusednetwork of carbon atoms that defines the graphene network itself.Typically, the carbon atoms defining the graphene or graphene oxidenetwork are arranged in a two-dimensional hexagonal or “honeycomb”structure. In some cases, the functional group bound to the graphenenetwork comprises a carbonyl group.

In some embodiments, the at least one functional group associated withgraphene or graphene oxide has the structure:

wherein R¹, R², and R³ can be the same or different, and each isindividually hydrogen or another suitable substituent, optionallysubstituted, and G comprises a carbon atom of the graphene or grapheneoxide. In some embodiments, G comprises a carbon atom positioned withinthe basal plane of the graphene or graphene oxide (e.g., G is aninterior carbon atom of the fused network of graphene or grapheneoxide). The term “substituent” as used herein will be understood bythose of ordinary skill in the art and refers to all permissiblesubstituents of the structure being referred to, “permissible” being inthe context of the chemical rules of valence known to those of ordinaryskill in the art. In some cases, the suitable substituent may be a salt.The suitable substituent may be an organic substituent or non-organicsubstituent.

In some cases, R¹ and R² can be the same or different and each areindependently hydrogen, alkyl, heteroalkyl, cycloalkyl, alkenyl, oraryl, any of which is optionally substituted. In some embodiments, R¹and R² are both hydrogen. In some cases, R³ is hydrogen, alkyl, aryl,alkenyl, cycloalkyl, heteroalkyl, heteroaryl, N(R⁴)₂, SR⁴, Si(R⁴)₂, OR⁴,or OM, any of which is optionally substituted, wherein M is a metal orcationic species and R⁴ is a suitable substituent (e.g., hydrogen, anorganic substituent, a metal-containing substituent), optionallysubstituted. In some cases, each R⁴ can be the same or different and arehydrogen, alkyl, cycloalkyl, haloalkyl, heteroalkyl, aryl, heteroaryl,or OH, any of which is optionally substituted. In some cases, at leastone of R¹, R², or R³ is haloalkyl. In a particular embodiment, R³ is OR⁴or N(R⁴)₂. In some embodiments, R⁴ is alkyl substituted with anunsubstituted or substituted aryl or an unsubstituted or substitutedcycloalkyl.

In some cases, R³ is N(CH₃)₂, NH-phenyl, NH-biphenyl, NHCH₂(CCH), OH,OMe, OEt, OM, where M is a metal ion, OCH₂(CCH), OCH₂CH₂(2-bromophenyl),OCH₂(adamantyl), or OCH₂C(4-chlorophenyl)₃.

In one set of embodiments, R¹ and R² are both hydrogen; and R³ is OH.

In one set of embodiments, R¹ and R² are both hydrogen; and R³ is OMe orOEt.

In some embodiments, the compositions and methods described hereincomprise carbon-based nanostructures (e.g., graphene oxide and/orgraphene) having a high density of functional groups. As used herein, acarbon-based nanostructure having a “high density of functional groups”refers to carbon-based nanostructures comprising a plurality offunctional groups attached to the surface of the nanostructure, whereinthe ratio of number of functional groups to number of carbon atoms ofthe surface of the nanostructure is at least about 1 to 50. The ratiomay also be considered in some embodiments as the surface density offunctional groups on the surface of the nanostructure for a given unitarea of the nanostructure, as defined by the number of carbon atomswithin that given unit area. In some cases, the ratio of functionalgroups to carbon atoms of the surface of the nanostructure is at leastabout 1 to 25, at least about 1 to 20, at least about 1 to 15, at least1 to 10, at least about 1 to 9, at least about 1 to 8, at least about 1to 7, at least about 1 to 6, at least about 1 to 5, at least about 2 to5, or, in some cases, at least about 1 to 4. Those of ordinary skill inthe art will be aware of methods and systems for determining the ratioof functional groups to carbon atoms of the surface of thenanostructure.

In some embodiments, methods are provided for forming functionalizedcarbon-based nanostructures (e.g., functionalized graphenes orfunctionalized graphene oxides). In some cases, the functionalizedcarbon-based nanostructure is formed utilizing graphene oxide as astarting material. Graphene oxide may be chemically converted to ahighly functionalized form of graphene or graphene oxide, in which atleast a portion of the carbon-oxygen chemical bonds of the grapheneoxide are transformed into carbon-carbon bonds. In some cases, anallylic alcohol functional group (e.g., a hydroxyl group with anadjacent olefinic double bond two carbon atoms away) commonly found on agraphene oxide surface is converted into an allylic carbon-carbon bond.In some cases, the allylic functional group alcohol is converted into anallylic carbon-carbon bond via an intermediary functional group, forexample, an allylic vinyl ether, an allylic ester, an allylic amide, anallylic ketone, an allylic ketene acetal, an allylic N,O-ketene acetal,a beta-keto allylic ester, an allylic silyl ketene acetal, an allyliclithium enolate, an allylic sodium enolate, an allylic zinc enolate, oran allylic glycolates. The intermediary allylic functional groups canundergo a rearrangement (e.g., a sigmatropic rearrangement), in whichthe carbon-oxygen bond is broken, the carbon-carbon allylic double bondshifts over one bond, and a new carbon-carbon single bond is formed onthe graphitic surface. A variety of pendant functional groups may begenerated associated with the graphene or graphene oxide via acarbon-carbon (e.g., single) bond depending on the reaction conditionsand the reagents employed. For example, graphene may be functionalizedwith moieties including aldehydes, carboxylic acids, esters, amides, andketones.

The methods described herein may involve treating the graphene orgraphene oxide with a reducing agent. For example, followingfunctionalization, any remaining unreacted oxygen functionalities on thegraphene or graphene oxide (e.g., unreacted allylic OH groups, etc.) maybe chemically reduced, for example, using reductants such as sodiumborohydride, lithium aluminum hydride, hydrazine, vitamin C (1-acsorbicacid), potassium hydroxide, thermal annealing, or ammonia. In someembodiments, the carbon-carbon bonds formed during the chemicalattachment of the at least one functional group to the graphene mayremain intact during and following the reduction conditions. In somecases, the resulting structure after chemical reduction is a highlyreduced graphene or graphene oxide that is surface functionalized with aplurality of functional groups attached via carbon-carbon bond linkages.

Various other chemical manipulations may also optionally be performed.For example, alcohols such as primary alcohols (e.g., present asunreacted oxygen functionalities on the reduced graphene surface asdescribed above or comprised in a functional group) may be reacted witha variety of electrophilic reagents. Alkylation and acylation of thealcohol groups may be performed in some embodiments, for example, viareaction of the modified reduced graphene with alkyl halides and acylhalides, respectively. Alkylation with perfluorinated alkyl halides maybe performed, in other embodiments. The pendant alcohol groups may alsoreadily react with epoxides to form beta-hydroxy ethers.

In some embodiments, the method comprises providing a carbon-basednanostructure comprising an allylic functional group (e.g., as may bepresent in graphene or graphene oxide). The carbon-based nanostructuremay be reacted with a reactant comprising at least one carbon atom toform a carbon-carbon bond between the at least one carbon atom withinthe reactant and a carbon atom within the carbon-based nanostructure.The term “allylic functional group,” as used herein in connection with acarbon-based nanostructure, refers to an allylic group which is aportion of the carbon-based nanostructure. Those of ordinary skill inthe art will understand the term allylic functional group as referringto a hydroxyl group or an OR group (R being a suitable substituent,including, but not limited to, alkyl, heteroalkyl, aryl, heteroaryl,etc., optionally substituted) with an adjacent olefinic double bond twocarbon atoms away, for example, having structures such as:

wherein C¹, C², and C³ are part of the carbon-based nanostructure (e.g.,the graphene carbon network). In some embodiments, the allylicfunctional group is positioned within the interior of the basal plane ofthe graphene or graphene oxide (e.g., not positioned at the edge orperimeter of the graphene or graphene oxide).

In some cases, the reacting step comprises reacting the carbon-basednanostructure with a reactant comprising at least one carbon atom, andtransforming the allylic functional group into a second allylicfunctional group. That is, in some cases, the allylic group isassociated with a first functional group (e.g., OR) and converted to asecond allylic group comprising a second functional group (e.g.,OC(R′)₂C(R″)₃). The second allylic group may undergo rearrangement,thereby forming a carbon-carbon bond between the at least one carbonatom within the reactant and a carbon atom within the carbon-basednanostructure (e.g., the first functional group may be associated withC³ of the allylic group, and the carbon-carbon bond may form between acarbon atom of the second functional group and C¹).

In some embodiments, the reactant is CH₃C(OCH₃)₃. In some embodiments,the reactant is an allylic ketene.

In some cases, a method for fabricating a functionalized carbon-basednanostructure (e.g., graphene) comprises providing a carbon-basednanostructure including a group having formula (I):

wherein C¹, C², and C³ are part of a fused network of aromatic ringswithin the carbon-based nanostructure and OR⁵ is a pendant group of thefused network of aromatic rings, wherein R⁵ is hydrogen or anothersuitable substituent, optionally substituted. In some embodiments, R⁵ ishydrogen, metal, alkyl, aryl, heteroalkyl, cycloalkyl, oroxygen-protection group, any of which is optionally substituted. Inparticular embodiments, R⁵ is hydrogen. The carbon-based nanostructuremay be reacted with a reactant to produce

wherein R⁶, R⁷, and R⁸ can be the same or different, and each isindependently selected from hydrogen or another suitable substituent,optionally substituted. In some cases, R⁶ and R⁷ can be the same ordifferent and each are independently hydrogen, alkyl, heteroalkyl,cycloalkyl, alkenyl, aryl, any of which is optionally substituted. Insome cases, R⁸ is hydrogen, alkyl, aryl, alkenyl, cycloalkyl,heteroalkyl, heteroaryl, N(R⁴)₂, SR⁴, Si(R⁴)₂, OR⁴, or OM, any of whichis optionally substituted, wherein M is a metal or cationic species andR⁴ is hydrogen or another suitable substituent, optionally substituted.In a particular embodiment, R⁸ is OR⁴ or N(R⁴)₂. In some cases, each R⁴can be the same or different and are hydrogen, alkyl, cycloalkyl,haloalkyl, heteroalkyl, heteroaryl, aryl, or OH, any of which isoptionally substituted.

In some embodiments, the formation of a compound of formula (II) from acompound of formula (I) (e.g., an allylic transposition) involves arearrangement reaction. For example, the allylic transposition may be asigmatropic rearrangement (e.g., a Claisen type rearrangement), anucleophilic substitution reaction, or a metal catalyzed reaction. Thoseof ordinary skill in the art will be aware of suitable reagents andreaction conditions (e.g., solvent conditions, temperature conditions,etc.) for carrying out a rearrangement reaction, in accordance with theinvention.

In some embodiments, the rearrangement is a traditional Claisenrearrangement (e.g., wherein the reagent is phenyl vinyl sulfoxide,ammonium betaines (e.g. 3-(trimethylammonio)acrylate)). In some cases,the rearrangement is an Ireland Claisen (e.g., wherein the reagents mayinclude acyl chloride, propanoyl chloride, and lithiumhexamethyldisilazide (e.g., a base)). In some cases, the rearrangementis a Johnson Claisen rearrangement (e.g., wherein the reagent may betriethylorthoformate, trimethylorthoformate, propionic acid (e.g., anacid source)). In some cases, the rearrangement may be an EschenmoserClaisen rearrangement, (e.g., wherein the reagent is dimethylacetamidedimethylacetal).

In other cases, the rearrangement may be a Carroll Claisen reaction(e.g., wherein the reagent is ethylacetoacetate), also referred to as a“Carroll reaction,” “Carroll rearrangement,” or “decarboxylativeallylation.” The Carroll rearrangement occurs when a β-keto allyl esterundergoes a [3,3] sigmatropic rearrangement to generate CO₂ and an allylketone. Typically, the β-keto allyl ester is heated, treated with base,or exposed to catalytic amounts of palladium. In some embodiments,graphene or graphene oxides functionalized with β-keto allyl esters maybe generated by reaction of graphene or graphene oxide with an acylketene, a high energy intermediate. In an illustrative embodiment, FIG.15A shows the reaction of graphene oxide with an acyl ketene to generatea β-keto allyl ester. Acyl ketenes can be generated using variousmethods known in the art, as shown in FIGS. 15B-D. One example isthermal fragmentation of acylated Meldrum's acid derivatives, Anotherexample involves coupling of Meldrum's acid with an carboxylic acid byway of a peptide coupling reagent such as N,N′-dicyclohexylcarbodiimideor diethyl cyanophosphate. Additionally, acyl ketenes can be thermallygenerated from dioxinone derivatives, as shown in FIG. 15C. In somecases, the surface of graphene or graphene oxide may be exposed to aβ-keto acid chloride and a non-nucleophilic base.

In some cases, reacting the carbon-based nanostructure with a reactantcauses a group having formula (I) to be converted to a group havingformula (III):

wherein R⁹, R¹⁰, and R¹¹ can be the same or different, and each isindependently selected from hydrogen or another suitable substituent,optionally substituted, or wherein R⁹ and R¹⁰ are joined together toform ═NR¹⁴ or ═O, and R¹⁴ is hydrogen or another suitable substituent,optionally substituted, n is 2 or 3, and

represents a single or double bond. The group having formula (III) maythen be converted to a group having formula (II), for example, via asigmatropic rearrangement. Generally, when the compound of formula (III)is rearranged to form a compound of formula (II), R⁸ is R⁹ or R¹⁰, or asalt or protonated version thereof, and R⁷ and R⁶ is an R¹¹ or a salt orprotonated version thereof.

In some cases, each R¹¹ can be the same or different and are hydrogen,alkyl, cycloalkyl, haloalkyl, heteroalkyl, alkenyl, aryl, heteroaryl,—OH, OR⁴ or —C(═O)R⁴ any of which is optionally substituted, wherein R⁴is hydrogen or another suitable substituent, optionally substituted oras defined herein. In some cases, R⁹, R¹⁰, and R¹⁴ are eachindependently hydrogen, alkyl, aryl, alkenyl, cycloalkyl, heteroalkyl,heteroaryl, N(R⁴)₂, SR⁴, Si(R⁴)₂, OR⁴, or OM, any of which is optionallysubstituted, wherein M is a metal (e.g., Na, Zn, K, Li, Ba, Ca) orcationic species and each R⁴ can be hydrogen or another suitablesubstituent, optionally substituted, or as defined herein.

In some cases, the compound of formula (III) comprising one of thefollowing structures:

wherein C¹, C², and C³ are part of the carbon-based nanostructure, andR¹¹, R⁴, and M are as defined herein. If more than one R¹¹ is present ina structure, the two R¹¹ moieties may be the same or different. In somecases, R⁴ is silicon, alkyl, heteroalkyl, alkenyl, or aryl, optionallysubstituted. Those of ordinary skill in the art will be aware ofsuitable reagents for forming a compound of formula (III).

In some embodiments, graphene oxide may be reacted with CH₃C(OCH₃)₃ toproduce a vinyl-ether intermediate that rearranges to produce the anallylic ester, as shown in FIG. 14A.

In some embodiments, graphene oxide may be reacted with an acyl ketene(e.g., O═C═C—(C═O)—R) to form a beta-keto-allyl ester, which can thenrearrange to form an allylic ketone, as shown in FIG. 15A.

Compositions described herein may find use in various applications. Inaddition, the association of a carbonyl group with a carbon-basednanostructure via a carbon-carbon bond may allow access to furtherfunctionalize the carbon-based nanostructure, thus allowing for thetuning of the mechanical and/or structural properties of thecarbon-based nanostructures. In some cases, the spacings betweengraphene sheets may be affected, at least in part, by the size, shape,chemical composition, and/or chemical affinity of the functional groups.For example, in some embodiments, if graphene oxide is used, the spacingbetween graphene layers can be tailored based on the type offunctionalization and substituents associated with the functional group.For example, larger groups associated with the graphene (e.g., R⁶-R⁸ incompound of formula (II)) may create larger interlayer spacings.Additional components could be contained within the interlayer spacesand may provide functions such as charge storage and/or ion conduction.As a specific example, graphite oxide (i.e., graphene oxide sheets) hasinterlayer spacings of about 8.4 Å, whereas graphene functionalized withCH₂C(═O)NMe₂ groups has interlayer spacings of about 9.3 Å.

The ability to incorporate components between interlayer spaces may beuseful for energy storage applications such as batteries, capacitors,etc. In some cases, the composition may be used as cathodes and/oranodes materials in batteries, or as a material in capacitors. Thus, insome embodiments, the spacing between carbon-based nanostructures (e.g.,graphene sheets) can be controlled by and/or tailored though the size,shape, chemical composition, and/or chemical affinity of the functionalgroups associated with the carbon-based nanostructure. In someembodiments, the functional groups may increase the ability of thecarbon-based nanostructure material to associate with and/or store redoxactive species (e.g., between interlayer spaces). In some cases, theredox active species may be lithium. In some cases, the composition maybe used to store charge, e.g., by incorporating the material into acharge storage device. In some cases, the charge storage device is acapacitor and/or an electrochemical double layer capacitor.

The properties of the compositions described herein may be tuned basedon the substitution of the carbonyl functional group. Those skilled inthe art would recognize what types of functional groups would afford aparticular, desired property, such as the ability to act as a filter orto determine an analyte or other species. In one set of embodiments, thecomposition may be functionalized with a binding site for determinationof a target analyte. For example, a sample suspected of containing ananalyte may be exposed to a composition as described herein. The analytemay interact with the composition to cause a change in a property of thecomposition, such as an optical property or an electrochemical property,wherein the change in the property may then determine the analyte. Asused herein, the term “determination” or “determining” generally refersto the analysis of a species or signal, for example, quantitatively orqualitatively, and/or the detection of the presence or absence of thespecies or signals. “Determination” or “determining” may also refer tothe analysis of an interaction between two or more species or signals,for example, quantitatively or qualitatively, and/or by detecting thepresence or absence of the interaction.

In some embodiments, the interaction between the composition and ananalyte may comprise formation of a bond, such as a covalent bond (e.g.carbon-carbon, carbon-oxygen, oxygen-silicon, sulfur-sulfur,phosphorus-nitrogen, carbon-nitrogen, metal-oxygen or other covalentbonds), an ionic bond, a hydrogen bond (e.g., between hydroxyl, amine,carboxyl, thiol and/or similar functional groups, for example), a dativebond (e.g. complexation or chelation between metal ions and monodentateor multidentate ligands), or the like. The interaction may also compriseVan der Waals interactions. In one embodiment, the interaction comprisesforming a covalent bond with an analyte. The binding site may alsointeract with an analyte via a binding event between pairs of biologicalmolecules. For example, the composition may comprise an entity, such asbiotin that specifically binds to a complementary entity, such as avidinor streptavidin, on a target analyte.

In some cases, the composition may comprise a biological or a chemicalmolecule able to bind to another biological or chemical molecule in amedium (e.g., solution, vapor phase, solid phase). For example, thebinding site may be a functional group, such as a thiol, aldehyde,ester, carboxylic acid, hydroxyl, or the like, wherein the functionalgroup forms a bond with the analyte. In some cases, the binding site maybe an electron-rich or electron-poor moiety within the composition,wherein interaction between the analyte and the composition comprises anelectrostatic interaction. For example, the composition may include anelectron-donating group and the analyte may include anelectron-withdrawing group. Alternatively, the composition may includean electron-withdrawing group and the analyte may include anelectron-donating group.

The composition may also be capable of biologically binding an analytevia an interaction that occurs between pairs of biological moleculesincluding proteins, nucleic acids, glycoproteins, carbohydrates,hormones, and the like. Specific examples include an antibody/peptidepair, an antibody/antigen pair, an antibody fragment/antigen pair, anantibody/antigen fragment pair, an antibody fragment/antigen fragmentpair, an antibody/hapten pair, an enzyme/substrate pair, anenzyme/inhibitor pair, an enzyme/cofactor pair, a protein/substratepair, a nucleic acid/nucleic acid pair, a protein/nucleic acid pair, apeptide/peptide pair, a protein/protein pair, a small molecule/proteinpair, a glutathione/GST pair, an anti-GFP/GFP fusion protein pair, aMyc/Max pair, a maltose/maltose binding protein pair, acarbohydrate/protein pair, a carbohydrate derivative/protein pair, ametal binding tag/metal/chelate, a peptide tag/metal ion-metal chelatepair, a peptide/NTA pair, a lectin/carbohydrate pair, a receptor/hormonepair, a receptor/effector pair, a complementary nucleic acid/nucleicacid pair, a ligand/cell surface receptor pair, a virus/ligand pair, aProtein A/antibody pair, a Protein G/antibody pair, a Protein L/antibodypair, an Fc receptor/antibody pair, a biotin/avidin pair, abiotin/streptavidin pair, a drug/target pair, a zinc finger/nucleic acidpair, a small molecule/peptide pair, a small molecule/protein pair, asmall molecule/target pair, a carbohydrate/protein pair such asmaltose/MBP (maltose binding protein), a small molecule/target pair, ora metal ion/chelating agent pair.

In some cases, the carbonyl functional groups may be furtherfunctionalized to incorporate functional groups capable of undergoingredox reactions (e.g., conducting polymer), which may lead toenhancement of the charge storage of these compositions. For example,bound amides may produce cyclic structures wherein the oxygen binds tocationic charges in a graphene layer that delocalizes the charge ontothe nitrogen atoms and can thereby enhance the charge storagecapabilities of the graphene. FIG. 9 shows an illustrative embodiment,where an oxidized graphene sheet functionalized with amide groups mayundergo a redox reaction such that charge from the graphene layer isdelocalized onto the amide nitrogen.

Accordingly, in some embodiments, the carbonyl species may befunctionalized with an electrochemically active functional group.Non-limiting examples of electrochemically active functional groupsinclude conducting polymers, metals, semi-metals, and/or semiconductors.In some cases, the functionalization contains amides which can formcyclic structures with the carbon-based nanostructure, wherein theoxygen binds to cationic charges in the carbon nanostructure. In somecases, the electrochemically active species is a species typically usedin batteries and would be readily identified by those skilled in theart.

In some embodiments, the composition may be appropriately functionalizedto impart desired characteristics (e.g., surface properties) to thecomposition. In some embodiments, the composition may include compounds,atoms, or materials that can alter or improve properties such ascompatibility with a suspension medium (e.g., water solubility, waterstability), photo-stability, and biocompatibility. In some cases, thecomposition comprises functional groups selected to possess an affinityfor a surface. For example, the composition may also be functionalizedto facilitate adsorption onto a particular surface, such as the surfaceof a substrate. In some embodiments, the composition is functionalizedwith carboxylic acid moieties, which may allow for electrostaticadsorption onto charged surfaces, such as glass surfaces, particlesurfaces, and the like.

In some cases, the carbonyl species may be functionalized such that thegraphene material is at least partially or substantially water-soluble.Examples include embodiments where the functional groups are—CH₂C(═O)NMe₂ or —CH₂C(═O)OR^(a), where R^(a) is hydrogen, alkyl,alkenyl, alkynyl, or aryl, any of which is optionally substituted, Insome embodiments, the functional groups may be saponified to form—CH₂CO₂H groups or a salt thereof. In such embodiments, the pH of aresulting solution of the graphene may be increased or decreased,thereby causing the carboxylic acid moieties to be either protonated orunprotonated. In some cases, the ability to alter between protonated andunprotonated forms of the graphene may aid in the purification,solubility, and/or stability of the graphene. For example, theprotonated form may be substantially insoluble in water and/or layers ofthe graphene may associated with each other, such that small colloidsand/or clusters of the graphene may form. In the unprotonated form, eachgraphene sheet may comprise a plurality of negative charges, such thatthe graphene is soluble or substantially soluble in water and/or eachgraphene layer is not associated with any other layers or graphenematerials (e.g., due to electrostatic repulsions of the layers). Forexample, see FIGS. 8 and 13 for illustrated examples of this process.Such a transition (e.g., from substantially soluble or soluble, tosubstantially insoluble or insoluble) may aid in purification of thematerial (e.g., by filtration, washing, etc.). Those of ordinary skillin the art will be aware of methods for saponifying amides (e.g., in thepresence of a base at elevated temperatures, for example, KOH inEtOH/H₂O at reflux).

Some embodiments provide stable, aqueous colloids or emulsionscomprising graphene species capable of remaining in solution without theneed for polymeric or surfactant stabilizers. The graphene species maybe substituted, for example, on the basal plane by allylic carboxylategroups. In some embodiments, the stability of an emulsion and/orcolloidal suspension may be determined based on the zeta-potential ofthe emulsion and/or colloidal suspension. Generally, emulsion/colloidalsuspension having a zeta-potential of about ±40 mV or greater areconsidered to have good stability. In some cases, the zeta-potential ofthe emulsion or colloid may be about ±20 mV, about ±30 mV, about ±35 mV,about ±40 mV, about ±45 mV, about ±50 mV, about ±55 mV, about ±60 mV,about ±65 mV, about ±70 mV, or greater.

In some cases, the compositions may include positively and/or negativelycharged functional groups.

The compositions and materials described herein may serve as effectivesubstrates for reducing the amount of, or even removing, a substance(e.g., toxic compounds) from a sample. In some cases, the sample is avapor phase sample. In some embodiments, the sample is a liquid sample.In some embodiments, the sample is an aerosol sample. The term “sample”refers to any material (e.g., in vapor phase, liquid phase, solid phase,aerosols, etc.) containing a species to be determined (e.g., ananalyte), purified, filtered, absorbed, adsorbed, chemically altered, orotherwise advantageously evaluated in accordance with the embodimentsdescribed herein. In some cases the sample is a vapor phase sample drawnor derived from a composition or device comprising nicotine (e.g., acigarette). In some cases, the sample may be drawn from a water supply.

For example, the method may involve contacting a vapor phase samplecontaining a first concentration of the species with a compositioncomprising substituted graphene or graphene oxide molecules. Uponcontacting the concentration, the vapor phase sample may have a second,decreased concentration of the species. In some embodiments, theconcentration of the species may be reduced by at least 5%, at least10%, at least 20%, at least 30%, at least 40%, at least 50%, at least60%, at least 70%, at least 80%, at least 90%, at least 95%, or, in somecases, at least 99%.

Without wishing to be bound any theory, the functionalized graphenes orgraphene oxides described herein may be particularly effective in theremoval or reduction in the amount of a substance in sample as theintersheet distance between adjacent graphene or graphene oxidemolecules may be advantageously varied (e.g., increased, decreased) tosuit a particular application, based on the functionalization on thebasal plane of the graphene or graphene oxide sheets. For example, thegraphene or graphene oxide sheets or may exhibit increased surface areato due at least in part to an increase in intersheet distance betweengraphene molecules or graphene oxide molecules. This may be attributedto functionalization on the basal plane of the graphene or grapheneoxide sheets by sterically large functional groups, and mayadvantageously allow for increased interaction (e.g., van der Waalsinteractions) between the composition and the sample. In someembodiments, the functional groups may be selected to have a particularsize to produce an intersheet distance capable of trapping orsequestering a particular analyte or species within the composition. Theability to covalently functionalize graphene or graphene oxide sheetswith a wide array of groups, as described herein, may also beadvantageous as the compositions may be tailored for specific targets.For example, functional groups which have known specific interactionswith potential contaminants may be appended onto graphene or grapheneoxide sheets, thereby turning the graphene or graphene oxide sheet intoa “super-ligand” for a wide range of substances, including toxicmaterials. Examples of such substances and samples are described herein.As an illustrative embodiment, a chelator such as dimercaprol or itsanalogs may be attached to a graphene or graphene oxide sheet in orderto trap heavy metals (e.g., Cd.

In some embodiments, the compositions may be used to selectively absorb,trap, and/or filter chemicals (e.g., gases and/or liquids). For example,the carbon-based nanostructure may be functionalized with groups such asperfluoroalkyl groups and/or nitroaromatic groups, which may interactwith (e.g., bind) toxins, pollutants, or other undesirable materials.The interaction may include an electrostatic interaction (e.g., betweenrelatively electron-rich moieties of a chemical and relativelyelectron-poor moieties of a carbon-based nanostructure), a non-covalentinteraction (e.g., binding interaction), a covalent interaction, or thelike. In an illustrative embodiment, the carbon-based nanostructure mayinclude a plurality of electron-poor nitroaromatic groups capable ofinteracting with (e.g., binding) electron rich groups of an organicpollutant via the nitroaromatic groups. In some embodiments, thecomposition may include orbitals (e.g., p-orbitals) that maysufficiently overlap with orbitals present on a particular analyte. Forexample, the interaction may involve pi-pi stacking between conjugatedpi-system of a high surface area graphene or graphene oxide withpolycyclic aromatic hydrocarbons, including undesirable components ofcigarette smoke, such as benzopyrene. In some cases, the analyte may bea metal ion (e.g., a heavy metal ion) having d-orbitals which overlapwith the pi-system of the functionalized graphene or graphene oxidesheets and/or various carbonyl groups on the graphene or graphene oxidesheets. Thus, compositions described herein may be useful for removingundesired chemicals from fluids or liquids.

In some embodiments, a composition described herein is used in a devicewhich functions as a filter, catalyst, and/or sensor.

In some embodiments, a device for filtering or reducing the amount of asubstance (e.g., a toxin, pollutant) in a sample may comprise acomposition described herein. The device and/or composition may becontacted with a sample containing an undesired substance, such as atoxin. The substance may be introduced to a device comprising thecomposition, and the composition may interact with the substance such itreduces the amount of the substance that exits the device. In somecases, prior to contact with the device and/or composition, the samplemay have a first concentration of a substance, and, after contacting thedevice and/or composition, the sample may have a second concentration ofthe substance, which is less than the first concentration. For example,the composition may physically prevent the substance from diffusing awayfrom the composition by binding or otherwise interacting with thesubstance. In some embodiments, the composition may interact with thesubstance to chemically alter the substance or convert the substanceinto a more desirable species, as described more fully below.

In some cases, the device filters, chemically alters, and/or sensesanalytes and other species including pollutants, toxins, and otherundesirable substances. In some cases, the analyte includes functionalgroups containing perfluoroalkyls or nitroaromatics. In someembodiments, the device may filter and/or sense nitroaromatic moleculesand other electron-poor molecules with electron-rich functional groups.

The analyte or species may be a chemical or biological analyte. Theanalyte or species may be any chemical, biochemical, or biologicalentity (e.g. a molecule) to be analyzed, including organic species,metal-containing species, metals and metal ions, or other inorganicspecies. In some cases, the composition may be selected to have highspecificity for the analyte. In some embodiments, the analyte comprisesa functional group that is capable of interacting with at least aportion of the composition, such as a functional group positioned on abasal plane of a graphene or graphene oxide sheet. For example, thefunctional group may interact with the analyte by forming a bond, suchas a covalent bond or a non-covalent bond. In some embodiments, thefunctional group may interact with the analyte by chemically alteringthe analyte. Some embodiments involve analytes comprisingelectron-withdrawing groups such as perfluoroalkyl groups and/ornitroaromatic groups.

Examples of analytes and species include, but are not limited to,various toxins, pollutants, such as tobacco-specific N-nitrosamines(TSNAs), hydrocarbons such as benzene or benzopyrene, pesticides,formaldehyde, metals including toxic metals, heavy metals, and/orradioactive metals such as arsenic, cadmium, lead 210, and the like,gases such as ammonia, carbon monoxide, hydrogen cyanide, and others. Insome embodiments, the analyte is carbon monoxide. In some embodiments,the analyte is a heavy metal.

In one set of embodiments, the compositions described herein may beuseful as cigarette filter materials. (FIG. 20) For example, thecomposition may be arranged in a cigarette, or related product or devicecontaining nicotine, and the sample contacting the composition may bevapor generated by the cigarette, i.e., cigarette smoke. The compositionmay be effective in reducing the amount of undesirable substances foundin cigarette smoke, including analytes as described herein.

Compositions described herein may also be appropriately functionalizedto serve as catalysts or as a support material for catalysts. In somecases, the functional groups comprise catalytic metals ormetal-containing groups, such as metal oxides. In certain cases, thefunctional groups comprise positively and/or negatively chargedfunctional groups which may bind metal ions capable of operating ascatalysts. In some cases, the functional groups function as metalbinding ligands, or ligands for metal-containing groups, and comprisenitrogen, sulfur, and/or phosphorus, thereby allowing the materials tofunction as a catalyst. In some embodiments, the bound metal ormetal-containing group (e.g., metal oxide) may be used for the reductionof oxygen (e.g., in a fuel cell). In certain cases, the bound metal mayoxidize and/or reduce water to make oxygen and/or hydrogen gases. Insome embodiments, the functional group may comprise a species capable ofreducing or oxidizing various species, including oxygen. Without wishingto be bound by any theory, covalent functionalization of graphene orgraphene oxide sheets on the basal plane may be advantageous in that theavailable surface area of the graphene would be altered (e.g.,increased, decreased), allowing for enhanced interaction with an analyteor other sample. Additionally, the composition includes covalent, andrelatively robust, attachment between the catalyst and the graphene orgraphene oxide sheets, potentially resulting in a more stable systemand/or enhanced catalytic rates.

As an illustrative embodiment, the compositions described herein may beused for oxidation of carbon monoxide to carbon dioxide. For example, afunctionalized graphene or graphene oxide containing a catalyst (e.g.,metal catalyst) may be prepared using methods described herein. Carbonmonoxide may interact with the catalyst attached to the graphene orgraphene oxide sheet and undergo the catalytic cycle to CO₂. In somecases, the composition (e.g., a composition comprising a Pd catalyst)may also be capable of reducing nitric oxide concurrently with oxidizingCO. Such methods may be useful, for example, in treating or filteringcigarette smoke to remove CO and/or NO. Those of ordinary skill in theart would be able to select various catalytic moieties capable ofoxidizing CO for use in the context of the embodiments described herein.In some cases, the catalytic moiety comprises Pd, Fe, Ce, Al, Cu, or Ti,or an oxide thereof. Examples of catalysts for CO oxidation include, butare not limited to, Pd nanoclusters, Fe₂O₃, FeOOH, or TiOOH.

In some cases, the functional group is capable of binding a metal atomor ion, and comprises nitrogen, sulfur, and/or phosphorus. In certainembodiments, the compositions described herein are used in a fuel cell.In some instances, compositions described herein are used for thereduction of water.

In some embodiments, the composition may be employed in composites formechanical property enhancement. For example, this may be accomplishedeither through a covalent linking of the carbon-based nanostructure(e.g., graphene) to the matrix or through functionalization of thecarbon-based nanostructure that allows for the carbon-basednanostructures to be dispersed throughout the matrix material.Additionally the functionalization of the carbon-based nanostructure maybe used to produce composites which are formed substantially fromgraphene or graphene oxide, wherein the graphene or graphene oxidesheets are associated with each other (e.g., via the functional groups).

Accordingly, in some embodiments, compositions described herein may bearranged in a composite material comprising a matrix material. In somecases, the carbon-based nanostructures are associated with the matrixmaterial via at least one covalent bond. In certain embodiments, thecovalent bond is form via an epoxide, amine, and/or urethane chemistriesknown to those skilled in the art. In some cases, a carbon-basednanostructure is functionalized such that the material can be dispersedthrough the matrix material. In some embodiments, the functional groupsof the carbon-based nanostructure are compatible and/or the same as thefunctional group of the matrix material. In certain instances, thefunctionalization has a negative Flory interaction parameter with thematrix material. In some embodiments, a carbon-based nanostructure islinked to a second carbon-based nanostructure via the functional groupsof each of the carbon-based nanostructures.

Those of ordinary skill in the art will be aware of various additionalapplications in which the compositions described herein may be employedand various methods and techniques for processing and forming devicescomprising the compositions provided herein.

The compositions described herein may also be useful as biologicalimaging agents, medical diagnostic agents, or biosensors. For example,carbon-based nanostructures comprising charged moieties may be useful asDNA diagnostics, wherein selection of the charged moieties may modulateinteraction of the carbon-based nanostructures with DNA molecules. Thecarbon-based nanostructures may be functionalized to increase ordecrease electrostatic interactions of the composition with DNA. In somecases, the carbon-based nanostructures may be assembled in combinationwith enzymes, or other biomolecules, for sensing applications.

In another set of embodiments, the composition may be useful in coatings(e.g., electrostatic assembly). For example, a composition may beassociated with a complementarily charged material (e.g., polymer, DNA,RNA, proteins, inorganic particles/clusters, individual metal ionsbearing multiple charges, carbon nanotubes, fullerenes, graphene, etc.).For example, the complementarily charged material may be positivelycharged and the composition may comprise negatively charged moieties,such the composition associated with the material and forms a coating onthe material. In some cases, the coating may substantially encapsulatethe material.

In some cases, the compositions may be used in optical applications. Insome embodiments, the compositions may have anisotropic structures thatmay interact with light (e.g., polarized light) selectively and giverise to polarized dependent properties.

In another set of embodiments, functionalized carbon-based nanostructuremay be useful as electron transport materials in photovoltaic devices.The functionalized carbon-based nanostructure may be combined with amaterial such as a conducting polymer, wherein the carbon-basednanostructure are functionalized with functional groups facilitating thestable formation of polymer blends, as described herein. In operation,the polymer matrix may act as an electron donor while the carbon-basednanostructure may act as the electron acceptors, wherein thecarbon-based nanostructures enhance the electron mobility through thedevice, resulting in photovoltaic devices having improved performance.

Compositions described herein may be useful in other applications,including chemical sensors, transistors (e.g., organic transistors),transparent conductive coatings, electrodes (e.g., forelectrocatalysis), components in photovoltaic devices, light-emittingdiodes (e.g., OLEDs, PLEDs, etc.), semiconductors, reinforcing elementsfor polymers including high strength polymers, composites, displays,actuators (e.g., polymer mechanical actuators), energystorage/production, circuits, flame retardant materials, and emissiveelements. In some cases, the compositions may be useful in cosmeticcompositions. In certain embodiments, the compositions may exhibit ionexchange properties and may be useful in water purification. Many otherapplications could benefit from the methods and compositions describedherein, including electronic materials for the semiconductor industry,gas-transport barrier agents for thermoplastic and thermoset resins(e.g., for food and beverage packaging), flame retardants, additives forautomotive fuel lines and gas tanks (e.g., as electrostatic dischargeprotection), additives for increased modulus and electrical conductivity(e.g., for electrostatic painting) in automotive body panels, conductiveadhesives, and electrode materials for rechargeable batteries andcapacitors

According to certain embodiments of the invention, a graphene dispersionor other dispersion using carbon-based nanostructures such as thosediscussed herein may be used in the application of thin coatings whichcould produce flexible, conductive, transparent electrodes (i.e.replacements for indium tin oxide coatings), conductive barrier in OLEDand organic photovoltaic (OPV) devices, non-halogenated fire retardantcoatings, as well as electrostatic discharge protection for plastics,e.g., due to the ability to control the spacing of such nanostructureswithin a material. Products such as moisture and oxygen barrier sealantsfor the organic photovoltaic (PV) and light emitting diode markets canalso be produced in some cases. Charge storage devices such asultracapacitors and rechargeable batteries can be produced that usegraphene or other compositions as described herein, e.g., as electrodes,in accordance with certain embodiments of the invention. The ability tochemically exfoliate and modify the surface of certain graphenestructures and reassemble the modified structures into a layeredstructure with specific inter-planar spacing may be used within suchenergy-storage devices, e.g., by allowing ions to be contained withinsuch layered structures. In certain embodiments, the ability tocontrollably functionalize the surface of certain graphene structures,and/or their spacing, allows the structures to be dispersed into aplastic or a polymer to modifying its strength, fracture toughness, heatdistortion temperature, moisture or oxygen diffusivities, and/orconductivities (both thermal and electrical). For example, a particularspacing of graphene structures may be selected in order to cause apolymer containing the graphene structure to exhibit a certain ionic orelectrical conductivity therein.

The methods of forming functionalized carbon-based nanostructures and/orvarious embodiments described herein may be carried out in any suitablesolvent, or combination thereof. Examples of solvents that may besuitable for use in the invention include, but are not limited to,benzene, p-cresol, toluene, xylene, mesitylene, diethyl ether, glycol,petroleum ether, hexane, cyclohexane, pentane, dichloromethane (ormethylene chloride), chloroform, carbon tetrachloride, dioxane,tetrahydrofuran (THF), dimethyl sulfoxide, dimethylformamide,hexamethyl-phosphoric triamide, ethyl acetate, pyridine, triethylamine,picoline, mixtures thereof, or the like.

The methods described herein may be carried out at any suitabletemperature(s). In some cases, the reaction is carried out at about roomtemperature (e.g., about 25° C., about 20° C., between about 20° C. andabout 25° C., or the like). In some cases, however, the reaction may becarried out at a temperature below or above room temperature, forexample, at about −70° C., about −50° C., about −30° C., about −10° C.,about −0° C., about 10° C., about 30° C., about 40° C., about 50° C.,about 60° C., about 70° C., about 80° C., about 90° C., about 100° C.,about 120° C., about 140° C., or the like. In some embodiments, thereaction may be carried out at more than one temperature (e.g.,reactants added at a first temperature and the reaction mixture agitatedat a second wherein the transition from a first temperature to a secondtemperature may be gradual or rapid).

A reaction may be allowed to proceed for any suitable period of time. Insome cases, the reaction is allowed to proceed for about 10 minutes,about 20 minutes, about 30 minutes, about 40 minutes, about 50 minutes,about 1 hour, about 2 hours, about 4 hours, about 8 hours, about 12hours, about 16 hours, about 24 hours, about 28 hours, or the like. Insome cases, aliquots of the reaction mixture may be removed and analyzedat an intermediate time to determine the progress of the reaction.

As used herein, a “carbon-based nanostructure” refers to acarbon-containing structure comprising a fused network of rings, such asaromatic rings. In some embodiments, the carbon-based nanostructurecomprises a fused network of at least 10, at least 20, at least 30, atleast 40, or, in some cases, at least 50 rings, at least 60 rings, atleast 70 rings, at least 80 rings, at least 100 rings, or more. Thecarbon-based nanostructure may be substantially planar or substantiallynon-planar, or may comprise planar and/or non-planar portions. Thecarbon-based nanostructure may optionally comprise a border at which thefused network terminates. For example, a sheet of graphite is a planarcarbon-based nanostructure comprising a border at which the fusednetwork terminates, while a fullerene is a nonplanar carbon-basednanostructure which lacks such a border. In some cases, the border maybe substituted with hydrogen atoms. In some cases, the border may besubstituted with groups comprising oxygen atoms (e.g., hydroxyl). Inother cases, the border may be substituted as described herein. The term“fused network” does not include, for example, a biphenyl group, whereintwo phenyl rings are joined by a single bond and are accordingly notfused together. Two rings are “fused” when there is at least one atompresent within the structure that can be simultaneously thought of asintegrally defining each of the two rings. In some cases, the fusednetwork may substantially comprise carbon atoms. In other cases, thefused network may comprise carbon atoms and heteroatoms. Some examplesof carbon-based nanostructures include graphene, carbon nanotubes (e.g.,single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes(MWCNTs)), fullerenes, and the like, as describe more herein. Also, asnoted above, other carbon-based materials (e.g. which may notnecessarily comprise nanostructures), such as carbon fibers, carbonfiber paper, activated carbon, and other materials that comprisecarbon-based structures comprising a fused network of rings (e.g.,aromatic rings) may be used in conjunction with the methods andcompositions of the present invention.

In some cases, the carbon-based nanostructure has an average maximumcross-sectional dimension of no more than about 1000 nm. In some cases,however, the maximum cross-sectional dimension may be greater than about1000 nm, for example, the carbon-based nanostructure has an averagemaximum cross-sectional dimension of no more than about 1 μm, about 2μm, about 3 μm, about 4 μm, about 5 μm, about 10 μm, or greater. In someembodiments, the carbon-based nanostructure may comprise at least about30%, at least about 40%, at least about 50%, at least about 60%, atleast about 70%, at least about 80%, at least about 90%, or at leastabout 95% of carbon by mass, or more. As used herein, the “maximumcross-sectional dimension” refers to the largest distance between twoopposed boundaries of an individual structure that may be measured.

In some cases, the carbon-based nanostructure may comprise a nonplanarportion, e.g., a curved portion having a convex surface and a concavesurface (where “surface,” in this context, defines a side of a moleculeor sheet defining a carbon-based nanostructure). Examples ofcarbon-based nanostructures comprising non-planar portions includefullerenes, carbon nanotubes, and fragments thereof, such ascorannulene. In some cases, the nonplanar aromatic portion may comprisecarbon atoms having a hybridization of sp^(2.x), wherein x is between 1and 9, i.e., the carbon atom may have hybridization between sp²- andsp³-hybridization, where this hybridization is characteristic ofnon-planarity of the molecule as would be understood by those ofordinary skill in the art. In these embodiments, x can also be between 2and 8, between 3 and 7, or between 4 and 6. x may also be 1, 2, 3, 4, 5,6, 7, 8, or 9, or fractions thereof. Typically, planar aromatic groupsand polycyclic aromatic groups (e.g., phenyl, naphthyl) may comprisecarbon atoms having sp² hybridization, while non-aromatic, non-planargroups (e.g., alkyl groups) may comprise carbon atoms having sp³hybridization. For carbon atoms in a nonplanar aromatic group, such as anonplanar portion of a carbon-based nanostructure, sp²-hybridized carbonatoms may be distorted (e.g., bent) to form the nonplanar or curvedportion of a carbon-based nanostructure. Without wishing to be bound bytheory, this distortion may cause angle strain and may alter thehybridization of the carbon atoms. As a result, the reactivity of thestrained carbon atoms may be enhanced.

In some cases, the carbon-based nanostructure may comprise an elongatedchemical structure having a diameter on the order of nanometers and alength on the order of microns (e.g., tens or microns, hundreds ofmicrons, etc.), resulting in an aspect ratio greater than 10, 100, 1000,10,000, or greater. In some cases, the carbon-based nanostructure mayhave a diameter less than 1 μm, less than 100 nm, 50 nm, less than 25nm, less than 10 nm, or, in some cases, less than 1 nm. For example, thecarbon-based nanostructure may have a cylindrical or pseudo-cylindricalshape (e.g., carbon nanotube).

In some cases, the carbon-based nanostructure comprises graphene (e.g.,graphene nanosheets). As used herein, the term “graphene” is given itsordinary meaning in the art and refers to polycyclic aromatic moleculesin which a plurality of carbon atoms is covalently bound to each other.The covalently bound carbon atoms form repeating units that comprise6-membered rings, but can also form 5-membered rings and/or 7-memberedrings. Accordingly, in graphene it appears as if the covalently boundcarbon atoms (usually, sp² carbons atoms) form a single layer having abasal plane comprising a fused network of aromatic rings. Graphenetypically includes at least one basal plane containing interior carbonatoms of the fused network, and a perimeter or edge containing theterminal carbon atoms of the fused network. Generally, the side ends oredges of the graphene are saturated with hydrogen atom. However, thegraphene material may contain non-carbon atoms at its edges, such as OHand COOH functionalities. It should be noted that the term “graphene”includes reference to both single atom layers of graphene and multiplelayer stacks of graphene.

In some cases, the carbon-based nanostructure is a carbon nanotube. Asused herein, the term “carbon nanotube” is given its ordinary meaning inthe art and refers to a substantially cylindrical molecule comprising afused network of six-membered aromatic rings. In some cases, carbonnanotubes may resemble a sheet of graphite rolled up into a seamlesscylindrical structure. It should be understood that the carbon nanotubemay also comprise rings other than six-membered rings. Typically, atleast one end of the carbon nanotube may be capped, i.e., with a curvedor nonplanar aromatic group, although in other embodiments, the carbonnanotube need not be capped. Carbon nanotubes may have a diameter of theorder of nanometers and a length on the order of micrometers, resultingin an aspect ratio greater than 100, 1000, 10,000, or greater. The term“carbon nanotube” includes single-walled nanotubes (SWCNTs),multi-walled nanotubes (MWCNTs) (e.g., concentric carbon nanotubes),inorganic derivatives thereof, and the like. In some embodiments, thecarbon nanotube is a single-walled carbon nanotube. In some cases, thecarbon nanotube is a multi-walled carbon nanotube (e.g., a double-walledcarbon nanotube).

In some cases, the carbon-based nanostructure is a fullerene. As usedherein, the term “fullerene” is given its ordinary meaning in the artand refers to a substantially spherical molecule generally comprising afused network of five-membered and/or six-membered aromatic rings. Forexample, C₆₀ is a fullerene which mimics the shape of a soccer ball. Theterm fullerene may also include molecules having a shape that is relatedto a spherical shape, such as an ellipsoid. It should be understood thatfullerenes may comprise rings other than five- or six-membered rings. Insome embodiments, the fullerene may comprise seven-membered rings, orlarger. Fullerenes may include C₃₆, C₅₀, C₆₀, C₇₀, C₇₆, C₈₄, and thelike.

As noted above, carbon-based nanostructures described herein may have ahigh density of charged moieties, i.e., may have a high ratio of chargedmoieties to double bonds on the outer surface of the carbon-basednanostructure. Those of ordinary skill in the art will be able todetermine the ratio of charged moieties to double bonds on the outersurface of the carbon-based nanostructure. For example, the number andtype of atoms or groups present within a carbon-based nanostructure canbe determined using differential scanning calorimetery thermogravimetricanalysis, spectrophotometric measurements, elemental analysis, etc. Inone example, a carbon-based nanostructure may be analyzed via elementalanalysis in order to calculate the ratio of charged moieties to doublebonds on the outer surface of the carbon-based nanostructure may becalculated.

In some cases, the carbon-based structure is a carbon fiber. As usedherein, the term “carbon fiber” is given its ordinary meaning in the artand refers to filamentary materials comprising carbon. In some cases,the carbon fiber includes at least about 50, 60, 70, 80, 90, or 95% byweight carbon. In some cases, the carbon fiber is in the form offilamentary tows having a plurality of individual filaments. Thediameter of the carbon fibers may be between about 1 um and about 1 mm,between about 5 um and about 100 μm, between about 5 μm and about 10 μm.In some cases, a plurality of carbon fibers may form carbon fiber paper,i.e., a two-dimensional sheet of carbon fibers. The fibers may bearranged randomly within the plane of the sheet.

As used herein, the term “react” or “reacting” refers to the formationof a bond between two or more components to produce a stable, isolablecompound. For example, a first component and a second component mayreact to form one reaction product comprising the first component andthe second component joined by a covalent bond. The term “reacting” mayalso include the use of solvents, catalysts, bases, ligands, or othermaterials which may serve to promote the occurrence of the reactionbetween component(s). A “stable, isolable compound” refers to isolatedreaction products and does not refer to unstable intermediates ortransition states. A variety of functional groups may be installed onthe carbon-based nanostructure by varying the alkyne (e.g.,electrophile) and nucleophile.

As used herein, the term “reacting” refers to the formation of a bondbetween two or more components to produce a compound. In some cases, thecompound is isolated. In some cases, the compound is not isolated and isformed in situ. For example, a first component and a second componentmay react to form one reaction product comprising the first componentand the second component joined by a covalent bond. That is, the term“reacting” does not refer to the interaction of solvents, catalysts,bases, ligands, or other materials which may serve to promote theoccurrence of the reaction with the component(s).

The term “substituted” is contemplated to include all permissiblesubstituents of organic compounds, “permissible” being in the context ofthe chemical rules of valence known to those of ordinary skill in theart. In some cases, “substituted” may generally refer to replacement ofa hydrogen with a substituent as described herein. However,“substituted,” as used herein, does not encompass replacement and/oralteration of a key functional group by which a molecule is identified,e.g., such that the “substituted” functional group becomes, throughsubstitution, a different functional group. For example, a “substitutedphenyl” must still comprise the phenyl moiety and can not be modified bysubstitution, in this definition, to become, e.g., a heteroaryl groupsuch as pyridine. In a broad aspect, the permissible substituentsinclude acyclic and cyclic, branched and unbranched, carbocyclic andheterocyclic, aromatic and nonaromatic substituents of organiccompounds. Illustrative substituents include, for example, thosedescribed herein. The permissible substituents can be one or more andthe same or different for appropriate organic compounds. For purposes ofthis invention, the heteroatoms such as nitrogen may have hydrogensubstituents and/or any permissible substituents of organic compoundsdescribed herein which satisfy the valencies of the heteroatoms. Thisinvention is not intended to be limited in any manner by the permissiblesubstituents of organic compounds.

Examples of substituents include, but are not limited to, alkyl, aryl,aralkyl, cyclic alkyl, heterocycloalkyl, hydroxy, alkoxy, aryloxy,perhaloalkoxy, aralkoxy, heteroaryl, heteroaryloxy, heteroarylalkyl,heteroaralkoxy, azido, amino, halogen, alkylthio, oxo, acylalkyl,carboxy esters, carboxyl, -carboxamido, nitro, acyloxy, aminoalkyl,alkylaminoaryl, alkylaryl, alkylaminoalkyl, alkoxyaryl, arylamino,aralkylamino, alkylsulfonyl, carboxamidoalkylaryl, carboxamidoaryl,hydroxyalkyl, haloalkyl, alkylaminoalkylcarboxy, aminocarboxamidoalkyl,alkoxyalkyl, perhaloalkyl, arylalkyloxyalkyl, and the like.

The term “aliphatic,” as used herein, includes both saturated andunsaturated, straight chain (i.e., unbranched) or branched aliphatichydrocarbons, which are optionally substituted with one or morefunctional groups. As will be appreciated by one of ordinary skill inthe art, “aliphatic” is intended herein to include, but is not limitedto, alkyl, alkenyl, alkynyl moieties. Thus, as used herein, the term“alkyl” includes straight and branched alkyl groups. An analogousconvention applies to other generic terms such as “alkenyl,” “alkynyl”and the like. Furthermore, as used herein, the terms “alkyl,” “alkenyl,”“alkynyl” and the like encompass both substituted and unsubstitutedgroups. In certain embodiments, as used herein, “lower alkyl” is used toindicate those alkyl groups (substituted or unsubstituted, branched orunbranched) having 1-6 carbon atoms.

In certain embodiments, the alkyl, alkenyl and alkynyl groups employedin the invention contain 1-20 aliphatic carbon atoms. In certain otherembodiments, the alkyl, alkenyl, and alkynyl groups employed in theinvention contain 1-10 aliphatic carbon atoms. In other embodiments, thealkyl, alkenyl, and alkynyl groups employed in the invention contain 1-8aliphatic carbon atoms. In still other embodiments, the alkyl, alkenyl,and alkynyl groups employed in the invention contain 1-6 aliphaticcarbon atoms. In other embodiments, the alkyl, alkenyl, and alkynylgroups employed in the invention contain 1-4 carbon atoms. Illustrativealiphatic groups thus include, but are not limited to, for example,methyl, ethyl, n-propyl, isopropyl, allyl, n-butyl, sec-butyl, isobutyl,tert-butyl, n-pentyl, sec-pentyl, isopentyl, tert-pentyl, n-hexyl,sec-hexyl, moieties and the like, which again, may bear one or moresubstituents. Alkenyl groups include, but are not limited to, forexample, ethenyl, propenyl, butenyl, 1-methyl-2-buten-1-yl, and thelike. Representative alkynyl groups include, but are not limited to,ethynyl, 2-propynyl (propargyl), 1-propynyl and the like.

The term “alicyclic,” as used herein, refers to compounds which combinethe properties of aliphatic and cyclic compounds and include but are notlimited to cyclic, or polycyclic aliphatic hydrocarbons and bridgedcycloalkyl compounds, which are optionally substituted with one or morefunctional groups. As will be appreciated by one of ordinary skill inthe art, “alicyclic” is intended herein to include, but is not limitedto, cycloalkyl, cycloalkenyl, and cycloalkynyl moieties, which areoptionally substituted with one or more functional groups. Illustrativealicyclic groups thus include, but are not limited to, for example,cyclopropyl, —CH₂-cyclopropyl, cyclobutyl, —CH₂-cyclobutyl, cyclopentyl,—CH₂-cyclopentyl, cyclohexyl, —CH₂-cyclohexyl, cyclohexenylethyl,cyclohexanylethyl, norborbyl moieties and the like, which again, maybear one or more substituents.

The term “heteroalkyl” is given its ordinary meaning in the art andrefers to alkyl groups as described herein in which one or more atoms isa heteroatom (e.g., oxygen, nitrogen, sulfur, and the like). Examples ofheteroalkyl groups include, but are not limited to, alkoxy,poly(ethylene glycol), alkyl-substituted amino, tetrahydrofuranyl,piperidinyl, morpholinyl, etc.

Some examples of substituents of the above-described aliphatic (andother) moieties of compounds of the invention include, but are notlimited to aliphatic; heteroaliphatic; aryl; heteroaryl; alkylaryl;alkylheteroaryl; alkoxy; aryloxy; heteroalkoxy; heteroaryloxy;alkylthio; arylthio; heteroalkylthio; heteroarylthio; F; Cl; Br; I; —OH;—NO₂; —CN; —CF₃; —CHF₂; —CH₂F; —CH₂CF₃; —CHCl₂; —CH₂OH; —CH₂CH₂OH;—CH₂NH₂; —CH₂SO₂CH₃; —C(O)R_(x); —CO₂(R_(x)); —CON(R_(x))₂; —OC(O)R_(x);—OCO₂R_(x); —OCON(R_(x))₂; —N(R_(x))₂; —S(O)₂R_(x); —NR_(x)(CO)R_(x)wherein each occurrence of R_(x) independently includes, but is notlimited to, aliphatic, alycyclic, heteroaliphatic, heterocyclic, aryl,heteroaryl, alkylaryl, or alkylheteroaryl, wherein any of the aliphatic,heteroaliphatic, alkylaryl, or alkylheteroaryl substituents describedabove and herein may be substituted or unsubstituted, branched orunbranched, cyclic or acyclic, and wherein any of the aryl or heteroarylsubstituents described above and herein may be substituted orunsubstituted. Additional examples of generally applicable substituentsare illustrated by the specific embodiments shown in the Examples thatare described herein.

In general, the term “aryl,” as used herein, refers to a stable mono- orpolycyclic, unsaturated moiety having preferably 3-14 carbon atoms, eachof which may be substituted or unsubstituted. In certain embodiments,the term “aryl” refers to a planar ring having p-orbitals perpendicularto the plane of the ring at each ring atom and satisfying the Huckelrule where the number of pi electrons in the ring is (4n+2) wherein n isan integer. A mono- or polycyclic, unsaturated moiety that does notsatisfy one or all of these criteria for aromaticity is defined hereinas “non-aromatic,” and is encompassed by the term “alicyclic.”

In general, the term “heteroaryl”, as used herein, refers to a stablemono- or polycyclic, unsaturated moiety having preferably 3-14 carbonatoms, each of which may be substituted or unsubstituted; and comprisingat least one heteroatom selected from O, S, and N within the ring (i.e.,in place of a ring carbon atom). In certain embodiments, the term“heteroaryl” refers to a planar ring comprising at least one heteroatom,having p-orbitals perpendicular to the plane of the ring at each ringatom, and satisfying the Huckel rule where the number of pi electrons inthe ring is (4n+2) wherein n is an integer.

It will also be appreciated that aryl and heteroaryl moieties, asdefined herein may be attached via an alkyl or heteroalkyl moiety andthus also include -(alkyl)aryl, -(heteroalkyl)aryl,-(heteroalkyl)heteroaryl, and -(heteroalkyl)heteroaryl moieties. Thus,as used herein, the phrases “aryl or heteroaryl moieties” and “aryl,heteroaryl, -(alkyl)aryl, -(heteroalkyl)aryl, -(heteroalkyl)heteroaryl,and -(heteroalkyl)heteroaryl” are interchangeable. Substituents include,but are not limited to, any of the previously mentioned substituents,i.e., the substituents recited for aliphatic moieties, or for othermoieties as disclosed herein, resulting in the formation of a stablecompound.

It will be appreciated that aryl and heteroaryl groups (includingbicyclic aryl groups) can be unsubstituted or substituted, whereinsubstitution includes replacement of one or more of the hydrogen atomsthereon independently with any one or more of the following moietiesincluding, but not limited to: aliphatic; alicyclic; heteroaliphatic;heterocyclic; aromatic; heteroaromatic; aryl; heteroaryl; alkylaryl;heteroalkylaryl; alkylheteroaryl; heteroalkylheteroaryl; alkoxy;aryloxy; heteroalkoxy; heteroaryloxy; alkylthio; arylthio;heteroalkylthio; heteroarylthio; F; Cl; Br; I; —OH; —NO₂; —CN; —CF₃;—CH₂F; —CHF₂; —CH₂CF₃; —CHCl₂; —CH₂OH; —CH₂CH₂OH; —CH₂NH₂; —CH₂SO₂CH₃;—C(O)R_(x); —CO₂(R_(x)); —CON(R_(x))₂; —OC(O)R_(x); —OCO₂R_(x);—OCON(R_(x))₂; —N(R_(x))₂; —S(O)R_(x); —S(O)₂R_(x); —NR_(x)(CO)R_(x)wherein each occurrence of R_(x) independently includes, but is notlimited to, aliphatic, alicyclic, heteroaliphatic, heterocyclic,aromatic, heteroaromatic, aryl, heteroaryl, alkylaryl, alkylheteroaryl,heteroalkylaryl or heteroalkylheteroaryl, wherein any of the aliphatic,alicyclic, heteroaliphatic, heterocyclic, alkylaryl, or alkylheteroarylsubstituents described above and herein may be substituted orunsubstituted, branched or unbranched, saturated or unsaturated, andwherein any of the aromatic, heteroaromatic, aryl, heteroaryl,-(alkyl)aryl or -(alkyl)heteroaryl substituents described above andherein may be substituted or unsubstituted. Additionally, it will beappreciated, that any two adjacent groups taken together may represent a4, 5, 6, or 7-membered substituted or unsubstituted alicyclic orheterocyclic moiety. Additional examples of generally applicablesubstituents are illustrated by the specific embodiments describedherein.

The term “cycloalkyl,” as used herein, refers specifically to groupshaving three to seven, preferably three to ten carbon atoms. Suitablecycloalkyls include, but are not limited to cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl and the like, which, as in the caseof aliphatic, alicyclic, heteroaliphatic or heterocyclic moieties, mayoptionally be substituted with substituents including, but not limitedto aliphatic; alicyclic; heteroaliphatic; heterocyclic; aromatic;heteroaromatic; aryl; heteroaryl; alkylaryl; heteroalkylaryl;alkylheteroaryl; heteroalkylheteroaryl; alkoxy; aryloxy; heteroalkoxy;heteroaryloxy; alkylthio; arylthio; heteroalkylthio; heteroarylthio; F;Cl; Br; I; —OH; —NO₂; —CN; —CF₃; —CH₂F; —CHF₂; —CH₂CF₃; —CHCl₂; —CH₂OH;—CH₂CH₂OH; —CH₂NH₂; —CH₂SO₂CH₃; —C(O)R_(x); —OC₂(R_(x)); —CON(R_(x))₂;—OC(O)R_(x); —OCO₂R_(x); —OCON(R_(x))₂; —N(R_(x))₂; —S(O)₂R_(x);—NR_(x)(CO)R_(x), wherein each occurrence of R_(x) independentlyincludes, but is not limited to, aliphatic, alicyclic, heteroaliphatic,heterocyclic, aromatic, heteroaromatic, aryl, heteroaryl, alkylaryl,alkylheteroaryl, heteroalkylaryl or heteroalkylheteroaryl, wherein anyof the aliphatic, alicyclic, heteroaliphatic, heterocyclic, alkylaryl,or alkylheteroaryl substituents described above and herein may besubstituted or unsubstituted, branched or unbranched, saturated orunsaturated, and wherein any of the aromatic, heteroaromatic, aryl orheteroaryl substituents described above and herein may be substituted orunsubstituted. Additional examples of generally applicable substituentsare illustrated by the specific embodiments shown in the Examples thatare described herein.

The term “heteroaliphatic,” as used herein, refers to aliphatic moietiesin which one or more carbon atoms in the main chain have beensubstituted with a heteroatom. Thus, a heteroaliphatic group refers toan aliphatic chain which contains one or more oxygen, sulfur, nitrogen,phosphorus or silicon atoms, e.g., in place of carbon atoms.Heteroaliphatic moieties may be linear or branched, and saturated orunsaturated. In certain embodiments, heteroaliphatic moieties aresubstituted by independent replacement of one or more of the hydrogenatoms thereon with one or more moieties including, but not limited toaliphatic; alicyclic; heteroaliphatic; heterocyclic; aromatic;heteroaromatic; aryl; heteroaryl; alkylaryl; alkylheteroaryl; alkoxy;aryloxy; heteroalkoxy; heteroaryloxy; alkylthio; arylthio;heteroalkylthio; heteroarylthio; F; Cl; Br; I; —OH; —NO₂; —CN; —CF₃;—CH₂F; —CHF₂; —CH₂CF₃; —CHCl₂; —CH₂OH; —CH₂CH₂OH; —CH₂NH₂; —CH₂SO₂CH₃;—C(O)R_(x); —OC₂(R_(x)); —CON(R_(x))₂; —OC(O)R_(x); —OCO₂R_(x);—OCON(R_(x))₂; —N(R_(x))₂; —S(O)₂R_(x); —NR_(x)(CO)R_(x) wherein eachoccurrence of R_(x) independently includes, but is not limited to,aliphatic, alicyclic, heteroaliphatic, heterocyclic, aromatic,heteroaromatic, aryl, heteroaryl, alkylaryl, alkylheteroaryl,heteroalkylaryl or heteroalkylheteroaryl, wherein any of the aliphatic,alicyclic, heteroaliphatic, heterocyclic, alkylaryl, or alkylheteroarylsubstituents described above and herein may be substituted orunsubstituted, branched or unbranched, saturated or unsaturated, andwherein any of the aromatic, heteroaromatic, aryl or heteroarylsubstituents described above and herein may be substituted orunsubstituted. Additional examples of generally applicable substituentsare illustrated by the specific embodiments described herein.

The term “heterocycloalkyl”, “heterocycle” or “heterocyclic”, as usedherein, refers to compounds which combine the properties ofheteroaliphatic and cyclic compounds and include, but are not limitedto, saturated and unsaturated mono- or polycyclic cyclic ring systemshaving 5-16 atoms wherein at least one ring atom is a heteroatomselected from O, S and N (wherein the nitrogen and sulfur heteroatomsmay be optionally be oxidized), wherein the ring systems are optionallysubstituted with one or more functional groups, as defined herein. Incertain embodiments, the term “heterocycloalkyl”, “heterocycle” or“heterocyclic” refers to a non-aromatic 5-, 6- or 7-membered ring or apolycyclic group wherein at least one ring atom is a heteroatom selectedfrom O, S, and N (wherein the nitrogen and sulfur heteroatoms may beoptionally be oxidized), including, but not limited to, a bi- ortri-cyclic group, comprising fused six-membered rings having between oneand three heteroatoms independently selected from oxygen, sulfur andnitrogen, wherein (i) each 5-membered ring has 0 to 2 double bonds, each6-membered ring has 0 to 2 double bonds and each 7-membered ring has 0to 3 double bonds, (ii) the nitrogen and sulfur heteroatoms may beoptionally be oxidized, (iii) the nitrogen heteroatom may optionally bequaternized, and (iv) any of the above heterocyclic rings may be fusedto an aryl or heteroaryl ring. Representative heterocycles include, butare not limited to, heterocycles such as furanyl, thiofuranyl, pyranyl,pyrrolyl, thienyl, pyrrolidinyl, pyrazolinyl, pyrazolidinyl,imidazolinyl, imidazolidinyl, piperidinyl, piperazinyl, oxazolyl,oxazolidinyl, isooxazolyl, isoxazolidinyl, dioxazolyl, thiadiazolyl,oxadiazolyl, tetrazolyl, triazolyl, thiatriazolyl, oxatriazolyl,thiadiazolyl, oxadiazolyl, morpholinyl, thiazolyl, thiazolidinyl,isothiazolyl, isothiazolidinyl, dithiazolyl, dithiazolidinyl,tetrahydrofuryl, and benzofused derivatives thereof. In certainembodiments, a “substituted heterocycle, or heterocycloalkyl orheterocyclic” group is utilized and as used herein, refers to aheterocycle, or heterocycloalkyl or heterocyclic group, as definedabove, substituted by the independent replacement of one, two or threeof the hydrogen atoms thereon with, but are not limited to, aliphatic;alicyclic; heteroaliphatic; heterocyclic; aromatic; heteroaromatic;aryl; heteroaryl; alkylaryl; heteroalkylaryl; alkylheteroaryl;heteroalkylheteroaryl; alkoxy; aryloxy; heteroalkoxy; heteroaryloxy;alkylthio; arylthio; heteroalkylthio; heteroarylthio; F; Cl; Br; I; —OH;—NO₂; —CN; —CF₃; —CH₂F; —CHF₂; —CH₂CF₃; —CHCl₂; —CH₂OH; —CH₂CH₂OH;—CH₂NH₂; —CH₂SO₂CH₃; —C(O)R_(x); —CO₂(R_(x)); —CON(R_(x))₂; —OC(O)R_(x);—OCO₂R_(x); —OCON(R_(x))₂; —N(R_(x))₂; —S(O)₂R_(x); —NR_(x)(CO)R_(x)wherein each occurrence of R_(x) independently includes, but is notlimited to, aliphatic, alicyclic, heteroaliphatic, heterocyclic,aromatic, heteroaromatic, aryl, heteroaryl, alkylaryl, alkylheteroaryl,heteroalkylaryl or heteroalkylheteroaryl, wherein any of the aliphatic,alicyclic, heteroaliphatic, heterocyclic, alkylaryl, or alkylheteroarylsubstituents described above and herein may be substituted orunsubstituted, branched or unbranched, saturated or unsaturated, andwherein any of the aromatic, heteroaromatic, aryl or heteroarylsubstituents described above and herein may be substituted orunsubstituted. Additional examples or generally applicable substituentsare illustrated by the specific embodiments described herein.

Additionally, it will be appreciated that any of the alicyclic orheterocyclic moieties described above and herein may comprise an aryl orheteroaryl moiety fused thereto. Additional examples of generallyapplicable substituents are illustrated by the specific embodimentsdescribed herein.

The terms “halo” and “halogen” as used herein refer to an atom selectedfrom fluorine, chlorine, bromine, and iodine.

The term “haloalkyl” denotes an alkyl group, as defined above, havingone, two, or three halogen atoms attached thereto and is exemplified bysuch groups as chloromethyl, bromoethyl, trifluoromethyl, and the like.

The term “amino,” as used herein, refers to a primary (—NH₂), secondary(—NHR_(x)), tertiary (—NR_(x)R_(y)), or quaternary (—N⁺R_(x)R_(y)R_(z))amine, where R_(x), R_(y) and R_(z) are independently an aliphatic,alicyclic, heteroaliphatic, heterocyclic, aryl, or heteroaryl moiety, asdefined herein. Examples of amino groups include, but are not limitedto, methylamino, dimethylamino, ethylamino, diethylamino,diethylaminocarbonyl, methylethylamino, iso-propylamino, piperidino,trimethylamino, and propylamino.

The term “alkyne” is given its ordinary meaning in the art and refers tobranched or unbranched unsaturated hydrocarbon groups containing atleast one triple bond. Non-limiting examples of alkynes includeacetylene, propyne, 1-butyne, 2-butyne, and the like. The alkyne groupmay be substituted and/or have one or more hydrogen atoms replaced witha functional group, such as a hydroxyl, halogen, alkoxy, and/or arylgroup.

The term “alkoxy” (or “alkyloxy”), or “thioalkyl” as used herein refersto an alkyl group, as previously defined, attached to the parentmolecular moiety through an oxygen atom or through a sulfur atom. Incertain embodiments, the alkyl group contains 1-20 aliphatic carbonatoms. In certain other embodiments, the alkyl group contains 1-10aliphatic carbon atoms. In other embodiments, the alkyl, alkenyl, andalkynyl groups employed in the invention contain 1-8 aliphatic carbonatoms. In still other embodiments, the alkyl group contains 1-6aliphatic carbon atoms. In other embodiments, the alkyl group contains1-4 aliphatic carbon atoms. Examples of alkoxy, include but are notlimited to, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, tert-butoxy,neopentoxy and n-hexoxy. Examples of thioalkyl include, but are notlimited to, methylthio, ethylthio, propylthio, isopropylthio,n-butylthio, and the like.

The term “alkoxy” refers to the group, —O-alkyl. The term “aryloxy”refers to the group, —O-aryl. The term “acyloxy” refers to the group,—O-acyl.

The term “independently selected” is used herein to indicate that the Rgroups can be identical or different.

These and other aspects described herein will be further appreciatedupon consideration of the following Examples, which are intended toillustrate certain particular embodiments of the invention but are notintended to limit its scope, as defined by the claims.

Example 1

The following example describes the direct conversion of carbon-oxygenbonds on a graphite oxide basal plane to carbon bound carbonyl groups(e.g., see FIG. 10). GO (graphene oxide) in this example wasfunctionalized using a Claisen rearrangement to allylically transposetertiary alcohol functional groups found throughout the basal plane ofgraphite oxide into carbon-bound carbonyl derivatives. In traditionalClaisen rearrangements, a vinyl allyl alcohol is heated tosimultaneously break a carbon-oxygen bond while forming a carbon-carbonbond (via a sigmatropic rearrangement). In this example the tertiaryalcohols that adorn the surface of graphite oxide function as thetertiary allylic alcohols. Direct treatment of these functional groupswith a vinyl group equivalent (e.g., dimethylacetamide dimethylacetal isshown in FIG. 10) forms a vinyl allyl alcohol on GO, in situ. Heatingthis modified GO then directly breaks the tertiary alcohol bond andallylically forms a new carbon-carbon bond while simultaneously formingthe new carbonyl derivative. In the FIG. 10, the newly formed carbonylderivative is an N,N-dimethylamide.

Functional density determination (the extent of functionalization, or“yield”) was carried out through the use of X-ray photoelectronicspectroscopy (XPS), thermogravemetric analysis (TGA), X-ray diffraction(XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy(FTIR). Analysis of the rearranged material indicated that not only werecarbonyl derivatives being successfully incorporated into the graphenesurface, but that the remaining, unreacted oxygen functionality wasbeing reduced during the course of the reaction. Therefore, this methodsimultaneously acts as a functionalization process as well as areduction process. Comparatively, this method reduces the graphene oxideto an equivalent degree to the most common chemical reduction methodutilizing hydrazine.

A variety of other reagents may be used to transform the allylictertiary alcohols on the surface of GO to vinyl allyl alcohols forsubsequent Claisen rearrangement. In particular, triethylorthoformate,trimethylorthoformate, CH₃C(OCH₃)₃ and ethylacetoacetate in combinationwith a weak Bronsted acid source may produce ester groups on the surfaceof graphene. Additionally, phenyl vinyl sulfoxides and ammonium betaines(e.g. 3-(trimethylammonio)acrylate) may produce aldehyde functionalityon the surface of graphene. Vinyl alcohol groups in the presence ofpalladium and mercury catalysts can also be used to form the necessaryvinyl allyl alcohol on GO.

Exemplary Methodology:

350 mg of graphite oxide and 350 mL of an appropriate dried and degassedsolvent (tetrahydrofuran-THF, dioxane, bis(2-methoxyethyl)ether) wereadded to a flame dried and argon filled flask. The solution wassonicated for 1 hour in a bath sonicator to achieve a fine dispersion.The solution was then brought to reflux and the dimethylacetamidedimethylacetal 2.4 mL (15.7 mmol, 2 times molar mass of oxygen contentin GO starting material). The mixture was refluxed for 24 h then cooledto room temperature. The dispersion was filtered through an anodesicmembrane (0.2 micron pore diameter) to obtain a filter cake. Thematerial was then washed with copious amounts of acetone followed bysonication in 20 mL of acetone for 1 h. The slurry was centrifuged at14,500 rpm to obtain a black sediment. Sonication in acetone andcentrifugation was repeated 3 times with acetone, 2 times with water andagain 2 times with acetone. The final sediment was dried under vacuum in40 degrees over KOH pellets.

Incorporation of carbonyl functionalized graphene derivatives as anelectronic component into devices allows graphene derivatives to be usedin a variety of applications. One such application would be in replacinggraphite as the commercial anode material for lithium ion batteries. Inthis context many attributes of the functionalized graphene derivativesdescribed above (carbonyl binding groups, large intersheet spacing,nanosheet structure, conductivity) should allow for high levels oflithium storage/intercalation into the nanosheets. Another applicationis the formation/binding of metallic nanoparticles on the surface of themodified graphene sheets. Not only could a nanoparticle-graphenederivative composite be produced by mixing the two substrates, but thecarbonyl functionality can also serve to “seed” the formation ofnanoparticles. In a similar capacity, the graphene derivatives can beused to chemically sense individual metal ions by measuring changes inthe conductivity of the graphene sheet upon binding the various metals.When bound to metal ions the graphene derivative can serve as a scaffoldfor catalytic processes. This is relevant for redox-type reactions inwhich, after the reaction, reduction of the metal ion can occurelectrochemically through the graphene backbone. Finally, the graphenederivatives can be utilized to serve as electron transportsemiconductors (n-type materials) in quantum dot based photovoltaicdevices.

Example 2

The following example described characterization of functionalizednanostructures formed using and/or comprising certain compositions ofthe present invention.

Reaction conditions for this example are substantially similar asdescribed in Example 1, except for variations in the solvent andtemperature. In addition, control reactions were carried out (e.g.,wherein no DMADMA was added to the reaction mixture).

In this example, the following abbreviations are employed, and arefurther described herein:

rGO1—reaction in THF at 60° C., DMADMA addedrGO1c—control reaction in THF at 60° C., no DMADMA addedrGO2—reaction in 1,4-dioxane at 100° C., DMADMA addedrGO2c—control reaction in 1,4-dioxane at 100° C., no DMADMA addedrGO3—reaction in diglyme at 150° C., DMADMA addedrGO3c—control reaction in diglyme at 150° C., no DMADMA added)rGO3b—reaction in diglyme sonicated for 3 h at pH=9rGO3b (500)—sample annealed in 500° C. for 6 h in N₂ atmosphere

Characterization: Throughout the course of the reaction, the reactionmixture turns black shortly after addition of DMA (FIG. 2). The rate ofcolor change is highest for highest reaction temperature indicatingpossible deoxygenation of GO. Specifically, FIG. 2 shows the reactionmixture (rGO3) before (on the left) and 60 s after (on the right)addition of DMA.

Incorporation of amide functionalities onto the surface of graphiteoxide (to yield rearranged graphite oxide, rGO) has been investigated bya wide variety of techniques: XPS, TGA, FTIR, XRD. XPS is the mostcommonly used technique for quantative as well as qualitativecharacterization of elemental composition of carbon materials. By XPSboth nitrogen incorporation as well as substantial deoxygenation of thesamples was confirmed. FIG. 2 show the XPS data for A) rGO3c and B)rGO3. Graphite oxide (GO) and material from control reactions (rGO1c,rGO2c, rGO3c) exhibit only two signals in XPS survey analysis,corresponding to the C1s (around 285 eV) and Ols (around 532 eV) peaks.The carbon to oxygen (C/O) ratio calculated according to atomic % is2.1, which is common for graphite oxides obtained by Hummer's method.All three rearranged graphite oxides (rGO1, rGO2, rGO3) show anadditional band attributed to the Nls peak (around 400 eV) as shown bysample XPS spectra in FIG. 2 show. FIG. 3 shows hi-res XPS data of (fromtop) C1s, O1s and N1s regions of (A) GO and (B) rGO3. Elementalcompositions of the samples (see Table 1) have been calculated. Nitrogenincorporation is higher with increasing reaction temperature.

Further work-up of the sample after reaction yields exfoliated material(rGO3b) with 3.7% nitrogen incorporation which corresponds to one—CH₂—C(O)N(CH₃)₂ group grafted on the surface of rGO per 18 C atoms (4-5rings) of the rearranged graphite oxide sheet. Oxygen species contentmay be higher than in rGO3 because of epoxide opening basic conditionsintroducing more oxygen species onto the surface of rearranged graphene.In some cases, the reaction causes simultaneous deoxygenation ofgraphite oxide at levels comparable to chemical methods of reduction.Some degree of deoxygenation can also be noticed in control reactionsbut it is generally lower (see Table 1 for C/O ratio). After annealingat 500° C., the amount of nitrogen was considerably smaller, forexample, due to cleavage of introduced groups, still accounting for 1introduced group per 57 graphene carbons that is approximately 20 rings.

By analysis of hi-res XPS data a drop in C—O species content was notedin the rearranged material both on the basis of C1sd and O1s signals. Inthe C1s region new components can be found attributed to amide moieties.The nitrogen band is composed of two separate peaks that can beattributed to amide and most probably charged amide functionalities.

TABLE 1 Atomic percentage for the analyzed samples calculated from XPSdata. C1s O1s N1s C/O* GO 68.1 31.9 — 2.1 rGO1 84.6 14.1 1.3 6.2 rGO285.5 12.4 2.1 6.3 rGO3 85.8 11.3 3.1 8.9 rGO3b 79.8 16.5 3.7 5.1 rGO3b(500) 85.7 12.9 1.4 7.0 rGO1c 74.0 26.0 — 4.0 rGO2c 75.5 24.5 — 3.0rGO3c 80.1 19.9 — 4.0 rGO3c 80.1 19.9 — 4.0 *C and O atoms of graphenesheets (without C and O in incorporated functionalities)

Deoxygenation of the material can be confirmed by TGA analysis. The TGAmass-loss curve of graphite oxide exhibits one mass loss region ataround 150° C. that is usually attributed to oxygen species. Afterrearrangement a gradual diminishing of this slope was observed andappearance of new mass loss region spanning from 230 to 400° C. (seeFIG. 4). Specifically, FIG. 4 shows (top) TGA and (bottom) dTGA (rate ofmass loss) of the samples. As has been demonstrated previously, in thistemperature range, one can observe loss of ligands bonded by C—C bondsto the reduced graphite sheet which may be occurring in this material.It is also conspicuous that the second slope is most pronounced forrGO3, which is the sample with highest level of functionalization(highest nitrogen incorporation as shown by XPS).

In x-ray diffraction experiments, GO exhibits a strong signalcorresponding to the typical graphite oxide spacing of 8.4 Å (10.5 Θ).After rearrangement moderately strong signal appears at 9.3 Å (9.4 Θ).Larger spacing than in GO is caused by incorporation of longersubstituents (—CH₂—C(O)N(CH₃)₂) on the reduced graphite oxide sheets incomparison to native groups (—O—, —OH). The spacing diminishes afterannealing at 500° C. to 4.2 Å which corresponds to decomposition ofintroduced groups. Weak and broad signals at 4.2 Å for GO and rGO3 canbe attributed to small domains of poorly exfoliated graphite regions ordeoxygenated domains of graphite oxide. FIG. 5 shows XRD spectra ofgraphite, GO and rGO3 samples.

FTIR analysis of GO reveals a series of characteristic signals: 1726cm⁻¹ C═O stretching vibrations from carbonyl and carboxyl groups, 1620cm⁻¹ C═C stretching, skeletal vibrations from unoxidized graphiticdomains, 1400 cm⁻¹ O—H bending vibrations, 1300-1350 cm⁻¹ C—OHstretching vibrations, 1200-1220 cm⁻¹ breathing vibrations from epoxygroups, 1060 cm⁻¹ v C—O. For rearranged samples a new signal at 1580cm⁻¹ can be observed that can be attributed to C═C bonds being morepronounced after deoxygenation. The strong signal at 1200 cm⁻¹ for rGO3indicates that epoxides are the main oxygen species in this material incontrast to the starting material (GO) which is in agreement with bothXPS data as well as reaction mechanism. FIG. 5 shows baseline correctedFTIR spectra of GO, rGO1 and rGO3.

rGO3b material can be easily dispersed in various organic solvents: NMP,DMF, ACN, and DMSO. Highest stability of dispersions was noted for DMF(0.1 mg/mL) with no precipitation observed after 3 weeks. FIG. 7 showsrGO3 solutions in (from right) DMF, NMP and ACN at 0.1 mg/mLconcentration after 3 weeks of sedimentation.

Example 3

The following example describes the synthesis of allylicamide-functionalized graphene. (FIGS. 11A-B). As shown in FIG. 11C,after 1 hour of reacting graphene oxide with [(CH₃)₂N]C(OCH₃)₂CH₃, thesolution turns black in color. Upon completion of the reaction, UV-visdata of the resulting material indicated re-establishment of aconjugated network, and an FTIR spectrum indicated the presence of amidegroups by the appearance of amide C═O stretching bands. (FIG. 11D) XRDdata for graphene, graphene oxide, and allylic amide-functionalizedgraphene oxide is shown in FIG. 11E. XPS plots for graphene oxide, andallylic amide-functionalized graphene oxide confirmed the presence ofamide functionality on the graphene surface (dialkylamides on activatedcarbon=399/9 eV). (FIGS. 11F-G) Furthermore, TGA data indicated that thefunctionalization was covalent in nature and that by increasing thereaction temperature, C—O functionalization decreased and C—Cfunctionalization increased.

Example 4

The following example describes saponification of modified grapheneoxide. FIG. 12A shows reaction conditions used for the saponification ofan allylic ester-functionalized graphene oxide. The XPS data shown inFIGS. 12B-C indicate that near-complete saponification of the dimethylamide group occurred to give a graphene sheet covalently functionalizedwith allylic carboxylates.

Example 5

The following example describes the formation of stable graphenecolloids using graphene substituted with allylic carboxylic acid groups.FIGS. 13A-B show the reversible conversion of carboxylicacid-functionalized graphene oxide to a potassium saltcarboxylate-functionalized graphene oxide. As shown in FIG. 13C, thechemically converted graphene sheets can form stable aqueous colloidsthrough electrostatic stabilization and can remain in solution withoutthe need for polymeric or surfactant stabilizers. FIG. 13D shows thezeta potential and conductivity data for carboxylic acid-functionalizedgraphene oxides.

Example 6

The following example describes the functionalization of graphene oxidevia a Johnson Claisen reaction using CH₃C(OCH₃)₃ to create a vinyl-etherintermediate that rearranges to form an allylic ester, which can befurther functionalized. (FIG. 14A) Examples of further functionalizationof the allylic ester include saponification (FIG. 14B), transamidation(FIG. 14C), as well as the synthesis of an alkyne-containing group foruse in click chemistry (FIG. 14D.

XRD was used to determine the distance between adjacent graphene sheetsfor various substituted graphene molecules, as shown in Table 2 below.Substitution on the basal plane of the graphene oxide sheets resulted inincreased intersheet distance, relative to unsubstituted graphenesheets.

TABLE 2 Intersheet distance for various substituted graphene molecules.Distance between two adjacent graphene Material sheets (Angstroms)Graphene 3.4 Graphene Oxide 8.49 Reduced GO (via NaBH₄) 5.5-3.4 (Adv.Func. Mater. 2009, 19, 1987.) Claisen-GO (graphene oxide substituted on9.93 basal plane with allylic ethyl esters) Reduced Claisen-GO (grapheneoxide 9.71 substituted on basal plane with allylic ethyl esters, uponbeing treated with a reducing agent) Amide Claisen GO - (graphene oxideR = H, 10.45 A, substituted on basal plane with allylic R = Ph, 10.65 Aamides)

Example 7

The following example describes the synthesis of functionalized grapheneoxides via a Carroll rearrangement. (FIG. 15B) All glassware wasflame-dried and the reactions were performed under nitrogen atmosphereusing standard Schlenk techniques. Graphite powder was received fromAlfa Aeser (natural, 325-mesh) and used without further purification.Graphite oxide was synthesized using a modified Hummer's method in whichNaNO₃ is excluded.

Acylated Meldrum's acid was synthesized according to the followingprocedure.

To form compound 2, 5.00 g (0.0218 mol) 3-(2-Bromophenyl)propanoic acidwas dissolved in 50 mL dry methylene chloride and the resulting solutionwas stirred and brought to 0° C. with an ice-bath and 0.1 mL DMF added.2.19 mL (3.19 g, 0.0251 mol, 1.15 eq) Freshly distilled oxalyl chloridewas added by syringe over 10 min, and the ice-bath removed. The reactionvessel was sealed and vented through an oil bubbler to monitor thereaction progress. After 4 hrs, or when the reaction was no longerevolving gas, the solution was degassed with argon for 10 min to promoteremoval of residual HCl.

While this reaction was degassing, 3.61 g Meldrum's acid (0.0251 mol,1.15 eq) was dissolved in 10 mL dry methylene chloride in a two-neckedround bottom flask. The clear solution was stirred brought to 0° C. withan ice-bath and 4.41 mL (4.31 g, 0.0545 mol, 2.5 eq) dry pyridine wasadded by syringe over 5 min. To this solution, the solution containingcompound 2 was added dropwise by cannula over 30 min. Upon addition theclear solution became an orange dispersion. After addition was complete,the reaction was stirred at 0° C. for 1 hr. Following this, the ice-bathwas removed and the reaction stirred at room temperature for an hour.The now deep red dispersion was poured into a 50 mL solution of 2 M HClcontaining ice. This mixture was then poured into a separatory funneland the organic layer isolated. The organic layer was washed with 2×50mL 2 M HCl and 1×50 mL brine, dried over MgSO4 and filtered. The deepred solution was adsorbed onto 5 g silica gel and purified by columnchromatography (eluent=9:1 hexanes:ethyl acetate, with 1% AcOH added) toproduce 6.51 g (0.0183 mol, 84% yield)5-(3-(2-bromophenyl)-1-hydroxypropylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione(compound 3).

The synthesis of a functionalized graphene oxide is described below.

20 mg Graphite oxide was dispersed in 100 mL dry diglyme (diethyleneglycol dimethyl ether). The dispersion was sonicated for 30 min and then0.005 mol (5 eq. to oxygen content of graphite oxide) acylated Meldrum'sacid was added. The dispersion was stirred for 1 hr at room temperaturethen immersed in a 100° C. oil bath. After approximately 10 min thepreviously brown dispersion turned black. After 4 hours, the oil bathtemperature was increased to 130° C., and the reaction stirred for 21hr. The black dispersion was filtered through a Millipore 0.4 μm PTFEmembrane. The resulting filter cake was washed with a copious amount ofacetone and then the black material was redispersed in 20 mL CH₂Cl₂. Thedispersion was vortexed for 10 seconds then centrifuged at 11000 rpm for10 min and the supernatant discarded. This procedure was repeated 3×with 20 mL CH₂Cl₂, followed by 2×20 mL acetone, 3×20 mL water, and 2×20mL acetone. The resulting black slurry was then dried in a vacuum ovenovernight at 50° C. to produce a fine black powder.

Alternatively, FIG. 15D shows another method for generating an acylketene. Heading 3-4 hours at 100 C, followed by 24 hours at 130 C.

Typically, two stages of heating were used, as graphite oxide oftenloses its oxygen functional groups upon heating and reduces back tographene. To maximize the chances that the acyl ketene produced willattach to an allylic alcohol, a temperature of 100° C. for 4 hours ismaintained to produce as many β-keto allyl esters on the surface ofgraphene as possible. The second stage of the transformation i.e., theCarroll rearrangement, is conducted at a relatively higher temperature.

FIG. 16 shows thermogravimetric analysis data for various functionalizedgraphenes compared to unsubstituted graphene and unsubstituted graphenewith physioadsorbed groups.

FIG. 17 shows X-ray diffraction data for graphene covalentlyfunctionalized on the basal plane, and FIG. 18 shows XPS data forgraphene covalently functionalized on the basal plane. Based on thisdata, the functionalization was shown to occur many times across thebasal plane of the graphene sheet, approximately once for every 20carbon rings. The R-groups on the basal plane created a regular latticewith increased D-spacings relative to reduced graphite and reducedgraphite oxide (3.3, 3.45 Å, respectively). XPS data also indicated thatgraphenes with heteroatoms (e.g., Br, Cl) include ˜1 functionalizationper 120 carbon atoms of graphene.

Additionally, it was found that functionalized graphenes can be used tocrease stable dispersions. FIG. 19 shows a photograph of various samplescontaining covalently functionalized graphene, graphene withphysioadsorbed groups, and unsubstituted graphene. It was observed thatgroups attached to graphene via non-covalent, physioadsorption did notimpart the same kind of dispersablility as group that are attached tothe basal plane of graphene covalently.

While several embodiments described herein have been described andillustrated herein, those of ordinary skill in the art will readilyenvision a variety of other means and/or structures for performing thefunctions and/or obtaining the results and/or one or more of theadvantages described herein, and each of such variations and/ormodifications is deemed to be within the scope of the present invention.More generally, those skilled in the art will readily appreciate thatall parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the teachings describedherein is/are used. Those skilled in the art will recognize, or be ableto ascertain using no more than routine experimentation, manyequivalents to the specific embodiments of the invention describedherein. It is, therefore, to be understood that the foregoingembodiments are presented by way of example only and that, within thescope of the appended claims and equivalents thereto, the invention maybe practiced otherwise than as specifically described and claimed. Thepresent invention is directed to each individual feature, system,article, material, kit, and/or method described herein. In addition, anycombination of two or more such features, systems, articles, materials,kits, and/or methods, if such features, systems, articles, materials,kits, and/or methods are not mutually inconsistent, is included withinthe scope of the present invention.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Other elements may optionallybe present other than the elements specifically identified by the“and/or” clause, whether related or unrelated to those elementsspecifically identified unless clearly indicated to the contrary. Thus,as a non-limiting example, a reference to “A and/or B,” when used inconjunction with open-ended language such as “comprising” can refer, inone embodiment, to A without B (optionally including elements other thanB); in another embodiment, to B without A (optionally including elementsother than A); in another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of.” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” and the like are to be understoodto be open-ended, i.e., to mean including but not limited to. Only thetransitional phrases “consisting of” and “consisting essentially of”shall be closed or semi-closed transitional phrases, respectively, asset forth in the United States Patent Office Manual of Patent ExaminingProcedures, Section 2111.03.

1. A method for reducing the amount of a species in a vapor phase sample, comprising: contacting a vapor phase sample containing a first concentration of the species with a composition comprising substituted graphene or graphene oxide molecules such that the vapor phase sample has a second, decreased concentration of the species after contact with the composition.
 2. A method for reducing the amount of a species in a sample, comprising: contacting a sample containing a first concentration of the species with a composition comprising graphene or graphene oxide, wherein the graphene or graphene oxide comprises at least one functional group having the structure:

wherein R¹, R², and R³ are the same or different and each is a substituent, optionally substituted; and G is a carbon atom of the graphene or graphene oxide, such that the sample has a second, decreased concentration of species after contact with the composition.
 3. A method as in claim 1, wherein the composition comprises a plurality of the graphene or graphene oxide molecules.
 4. A method as in claim 1, wherein the composition comprises an electron-donating group and the species comprises an electron-withdrawing group.
 5. A method as in claim 1, wherein the species is a toxin or pollutant.
 6. A method as in claim 5, wherein the species is carbon monoxide.
 7. A method as in claim 1, wherein the species is a heavy metal.
 8. A method as in claim 1, wherein the sample comprises cigarette smoke.
 9. A method as in claim 1, wherein the composition is arranged in a cigarette.
 10. A method as in claim 1, wherein the composition comprises graphene or graphene oxide comprising at least one functional group associated with the graphene or graphene oxide, wherein the at least one functional group has the structure:

wherein R¹, R², and R³ are the same or different and each is independently a substituent, optionally substituted; and G is a carbon atom of the graphene or graphene oxide.
 11. A method as in claim 10, wherein: R¹ and R² are the same or different and each is independently hydrogen, alkyl, heteroalkyl, cycloalkyl, alkenyl, or aryl, any of which is optionally substituted.
 12. A method as in claim 11, wherein R¹ and R² are both hydrogen.
 13. A method as in claim 12, wherein: R³ is hydrogen, alkyl, aryl, alkenyl, cycloalkyl, heteroalkyl, heteroaryl, N(R⁴)₂, SR⁴, Si(R⁴)₂, OR⁴, or OM, any of which is optionally substituted, M is a metal or cationic species; and each R⁴ is independently a substituent, optionally substituted.
 14. A method as in claim 10, wherein at least one of R¹, R², or R³ is haloalkyl.
 15. A method as in claim 10, wherein R³ is OR⁴ or N(R⁴)₂ and each R⁴ is independently a substituent, optionally substituted.
 16. A method as in claim 15, wherein each R⁴ is the same or different and each is independently hydrogen, alkyl, cycloalkyl, haloalkyl, heteroalkyl, aryl, heteroaryl, or OH, any of which is optionally substituted.
 17. A method as in claim 16, wherein R⁴ is alkyl substituted with an unsubstituted or substituted aryl or an unsubstituted or substituted cycloalkyl.
 18. A method as in claim 15, wherein R³ is N(CH₃)₂, NH-phenyl, NH-biphenyl, NHCH₂(CCH), OH, OMe, OEt, OM, where M is a metal ion, OCH₂(CCH), OCH₂CH₂(2-bromophenyl), OCH₂(adamantyl), or OCH₂C(4-chlorophenyl)₃.
 19. A method as in claim 10, wherein R¹ and R² are both hydrogen; and R³ is OH.
 20. A method as in claim 10, wherein R¹ and R² are both hydrogen; and R³ is OMe or OEt.
 21. A method as in claim 10, wherein the ratio of the number of functional groups to the number of carbon atom of the graphene or graphene oxide is at least about 1 to 50, or at least about 1 to 25, or at least about 1 to 20, or at least about 1 to 15, or at least 1 to 10, or at least about 1 to
 5. 22. A method as in claim 10, wherein the functional group is capable of binding a metal ion.
 23. A method as in claim 10, wherein the functional group comprises positively or negatively charged groups.
 24. A method as in claim 10, wherein the functional group comprises an electrochemically active species.
 25. A method as in claim 24, wherein the electrochemically active species is a conducting polymer, metal, semi-metal, or semiconductors.
 26. A method as in claim 24, wherein the electrochemically active species comprises an amide.
 27. A method as in claim 10, wherein the functional group is capable of oxidizing carbon monoxide.
 28. A method as in claim 10, wherein the functional group is capable of reducing oxygen.
 29. A method as in claim 10, wherein the functional group is capable of reducing nitric oxide.
 30. A method as in claim 10, wherein the functional group is capable of associating with and/or storing redox active species.
 31. A method as in claim 30, wherein the redox species is lithium.
 32. A method as in claim 1, wherein the composition is arranged in an anode or cathode of a battery.
 33. A catalyst composition for oxidation of carbon monoxide, comprising: a graphene or graphene oxide molecule comprising at least one functional group having the structure:

wherein: R¹, R², and R³ are the same or different and each is independently a substituent, optionally substituted, wherein at least one of R¹, R², and R³ comprises a catalytic moiety capable of oxidizing carbon monoxide to carbon dioxide; and G is a carbon atom of the graphene or graphene oxide.
 34. A catalyst composition as in claim 33, wherein the catalytic moiety comprises a metal.
 35. A catalyst composition as in claim 33, wherein the catalytic moiety comprises Pd, Fe, Ce, Al, Cu, or Ti, or an oxide thereof.
 36. A catalyst composition as in claim 33, wherein the catalytic moiety comprises Pd nanoclusters, Fe₂O₃, FeOOH, or TiOOH.
 37. A method for oxidation of carbon monoxide, comprising: contacting a sample comprising carbon monoxide with a graphene or graphene oxide molecule comprising at least one functional group having the structure:

wherein: R¹, R², and R³ are the same or different and each is independently hydrogen or a substituent, optionally substituted; and G is a carbon atom of the graphene or graphene oxide.
 38. A method as in claim 37, wherein the functional group comprises a catalytic moiety capable of oxidizing carbon monoxide.
 39. A method as in claim 38, wherein the catalytic moiety comprises a metal.
 40. A method as in claim 39, wherein the catalytic moiety comprises Pd, Fe, Ce, Al, Cu, or Ti, or an oxide thereof.
 41. A method as in claim 40, wherein the catalytic moiety comprises Pd nanoclusters, Fe₂O₃, FeOOH, or TiOOH.
 42. A method as in claim 37, wherein the sample comprises cigarette smoke.
 43. A method as in claim 37, wherein the graphene or graphene oxide molecule is arranged in a cigarette.
 44. A method as in claim 37, wherein: R¹ and R² are the same or different and each is independently hydrogen, alkyl, heteroalkyl, cycloalkyl, alkenyl, or aryl, any of which is optionally substituted.
 45. A method as in claim 44, wherein R¹ and R² are both hydrogen.
 46. A method as in claim 37, wherein: R³ is hydrogen, alkyl, aryl, alkenyl, cycloalkyl, heteroalkyl, heteroaryl, N(R⁴)₂, SR⁴, Si(R⁴)₂, OR⁴, or OM, any of which is optionally substituted, M is a metal or cationic species; and each R⁴ is independently a substituent, optionally substituted.
 47. A method as in claim 37, wherein at least one of R¹, R², or R³ is haloalkyl.
 48. A method as in claim 37, wherein R³ is OR⁴ or N(R⁴)₂ and each R⁴ is independently a substituent, optionally substituted.
 49. A method as in claim 37, wherein each R⁴ is the same or different and each is independently hydrogen, alkyl, cycloalkyl, haloalkyl, heteroalkyl, aryl, heteroaryl, or OH, any of which is optionally substituted.
 50. A method as in claim 49, wherein R⁴ is alkyl substituted with an unsubstituted or substituted aryl or an unsubstituted or substituted cycloalkyl.
 51. A method as in claim 48, wherein R³ is N(CH₃)₂, NH-phenyl, NH-biphenyl, NHCH₂(CCH), OH, OMe, OEt, OM, where M is a metal ion, OCH₂(CCH), OCH₂CH₂(2-bromophenyl), OCH₂(adamantyl), or OCH₂C(4-chlorophenyl)₃.
 52. A method as in claim 49, wherein R¹ and R² are both hydrogen; and R³ is OH.
 53. A method as in claim 37, wherein R¹ and R² are both hydrogen; and R³ is OMe or OEt.
 54. A method as in claim 37, wherein the ratio of the number of functional groups to the number of carbon atom of the graphene or graphene oxide is at least about 1 to 50, or at least about 1 to 25, or at least about 1 to 20, or at least about 1 to 15, or at least 1 to 10, or at least about 1 to
 5. 55. A method as in claim 37, wherein the functional group is capable of binding a metal ion.
 56. A method as in claim 37, wherein the functional group comprises positively or negatively charged groups.
 57. A method as in claim 37, wherein the functional group comprises an electrochemically active species.
 58. A method as in claim 57, wherein the electrochemically active species is a conducting polymer, metal, semi-metal, or semiconductors.
 59. A method as in claim 57, wherein the electrochemically active species comprises an amide.
 60. A method as in claim 37, wherein the functional group is capable of oxidizing carbon monoxide.
 61. A method as in claim 37, wherein the functional group is capable of reducing oxygen.
 62. A method as in claim 37, wherein the functional group is capable of associating with and/or storing redox active species.
 63. A method as in claim 62, wherein the redox species is lithium. 